30 Hours After the Quake, One Kumamoto Fab Was Already Running — What Split the Recovery Wasn't the Buildings

[July 31 evening update] Sony, which this article had identified as the "only operator without a restart plan," disclosed its recovery plan in an official second statement dated July 31. The Kumamoto Technology Center (Kikuyo Town) said that, "having completed safety checks and recovery work on the building and equipment," it "plans to resume operations progressively from Tuesday, August 4," and "expects to return to pre-earthquake production levels by mid-August." The silence was broken on the afternoon of day four. Tokyo's market close saw the Nikkei average surge 2,494 points, with chip stocks rising broadly, but the main driver cited for the close was a reassessment following strong US tech earnings, and no link to Kumamoto's earthquake recovery has been confirmed (Sony Semiconductor Solutions; Jiji Press, July 31, 2026). The body text below reflects the state of things as of the morning of July 31; subsequent updates have been appended at the end of each relevant section.

[July 31 night update] For the first time at a Kumamoto semiconductor site, a plant has returned to "pre-earthquake production capacity." In its third statement on July 31, Renesas said the Nishiki plant "resumed production progressively from the night of July 29, and returned to pre-earthquake production capacity this morning." The Kawajiri plant, too, plans to return to pre-earthquake production capacity "within about three weeks" of its August 5 restart. The impact on automobiles, meanwhile, has only widened. Toyota disclosed it would halt its Tahara plant in Aichi Prefecture from August 3 to 7, and Honda extended the halt at its Kumamoto plant through August 7. The cause is that Aisin Kyushu, in Kumamoto City, was damaged in the quake and has cut off the supply of key car-door components. One industry's machines are starting up again while the other's stay silent — on day four of the same earthquake, the clocks of two industries are running in opposite directions (Renesas official statement; Jiji Press, July 31, 2026).

This article organizes the situation as of the morning of July 31 — day four of the earthquake — following our day-3 update from midday July 30. Please also see our day-2 follow-up from July 29 and our initial status report from the night of the quake, July 28. Between the night of July 29 and the morning of July 31, a string of developments emerged: Renesas's Nishiki plant restarting, details of Mitsubishi Electric's partial restart, and a third-party analyst's estimate of the impact on TSMC subsidiary JASM. Building on these, this article organizes the situation around two questions: "why did the recovery speed split so sharply?" and "if the impact is small, is it safe to relax?"

Why could the Nishiki plant restart within 30 hours?

Renesas Electronics issued its second official statement since the earthquake at 5:18 p.m. on July 30. According to the statement, the Nishiki plant (Nishiki Town, Kuma District), after completing cleanroom safety checks, has been resuming production progressively since the night of July 29 — about 30 hours after the earthquake struck (per Renesas's official statement, 5:18 p.m., July 30, 2026).

The reason the plant could restart so quickly is that, even with damage such as some ceiling panels falling and cracked walls, its air conditioning and power supply held up, and the cleanliness of the cleanroom itself — a particle-controlled clean space — was preserved. As explained in our previous update, when a cleanroom's air conditioning and power hold up, a fab doesn't need to redo its "cleanroom certification" — the process of confirming particle-concentration and other standards are met — and recovery is that much faster. The Nishiki plant's 30-hour restart is exactly this structure playing out.

Meanwhile, Renesas's other Kumamoto plant, Kawajiri (Minami-ku, Kumamoto City), was announced as scheduled to resume production progressively from August 5 (per Renesas's official statement, 5:18 p.m., July 30, 2026). This, too, is only a plan — not a confirmed date. As the word "progressively" suggests, neither plant is returning to full operation all at once; both continue a staged startup. Kumamoto Nichinichi Shimbun reported the same details in its 10:16 p.m. filing on July 30 (Kumamoto Nichinichi Shimbun, July 30, 2026).

Mitsubishi Electric shows a similar pattern. Its Koshi and Kikuchi plants are "operating equipment progressively, from the equipment cleared as safe, with no major damage to the buildings," and there have been no employee injuries (Kumamoto Nichinichi Shimbun, 7:59 p.m., July 30, 2026). Still, only some processes have restarted, and the timing of a full restart remains undecided. Tokyo Electron Kyushu, too, is reported to have sustained no major damage to buildings or equipment at either its Koshi or Otsu sites, and plans to resume full production from August 3 (Yomiuri Shimbun, July 30, 2026). Even where "the building is intact" and "restart is progressive" hold in common, how far each company has come in restoring its processes still varies.

[July 31 night update] On July 31, Renesas issued its third official statement since the earthquake, titled "Impact of the 2026 Kumamoto Earthquake on Our Business Activities (Third Report)." Verbatim, it states that the Nishiki plant "resumed production progressively from the night of July 29, and returned to pre-earthquake production capacity this morning." The progressive restart that began on the night of July 29 reached full pre-earthquake production capacity in roughly a day and a half, by the morning of July 31 — the first Kumamoto semiconductor site to reach that milestone. As for the Kawajiri plant, the statement says it is "scheduled to resume production progressively from August 5," and Renesas aims to bring it back to pre-earthquake production capacity (on a production-start basis) "within about three weeks" of that restart (Renesas's official third statement, July 31, 2026). Where the Nishiki plant's 30-hour restart was a measure of "how fast a fab can start moving again," this third statement points to the next benchmark: how fast it can climb back to its original capacity once it has restarted — a process the Kawajiri plant has yet to go through.

Why was Sony's Kikuyo plant alone still silent on day four?

As of the morning of July 31, Sony Semiconductor Solutions' most recent official notice was still the one dated July 29. Its Kumamoto Technology Center (Kikuyo Town) has halted production, and the notice — which said it was still checking the condition of buildings and facilities — made no mention of a restart timeline (Sony Semiconductor Solutions, official notice dated July 29, 2026).

Nikkei, in an article filed at 5:00 a.m. on July 31, ran the headline "Renesas, Tokyo Electron resume production progressively in Kumamoto; Sony taking time to confirm damage," reporting that Sony was the only one of Kumamoto's major operators still without a restart timeline (Nikkei, filed 5:00 a.m., July 31, 2026).

No specifics about the damage or a restart timeline have yet been given, and this article does not speculate about the damage or state anything as fact beyond what's confirmed. What is known is only this: as of the morning of July 31, Sony alone was left behind. Within the same earthquake and the same four days, one plant is running and another still cannot run — and that gap itself is the single most important thing to understand about how this Kumamoto earthquake's recovery has unfolded.

[July 31 evening update] Sony Semiconductor Solutions issued an official second statement dated July 31, titled "On the impact of the 2026 Kumamoto earthquake (second report)." Verbatim, it says: "Having completed safety checks and recovery work on the building and equipment, we plan to resume operations progressively from Tuesday, August 4. We expect to return to pre-earthquake production levels by mid-August." It gives no specific description of damage (Sony Semiconductor Solutions, July 31, 2026). No timeline had been given on the morning of day four, but a restart plan emerged that same afternoon. Sony's silence, it turns out, did not mean it "couldn't recover" — it meant the company was taking time over damage confirmation and recovery work. With this, every major Kumamoto operator has now either restarted or announced a restart date (with the exception of JASM's declaration of full recovery).

If the impact is only 0.03%, is it safe to relax?

DIGITIMES analyst Huang Chien-chih, in a report filed at 11:14 a.m. on July 30 (Taipei, distributed via CNA), estimated that even in a worst-case scenario where JASM halts for a full week and recovers none of that lost production, the impact on revenue would be limited to about US$14 million. That is just about 0.03% of TSMC's Q3 2026 revenue guidance midpoint of $45.2 billion (official range $44.6-45.8 billion), disclosed at its July 16 earnings call (CNA, July 30, 2026). It bears noting, though, that this is a third-party analyst's estimate — not a figure TSMC itself has disclosed.

Huang attached conditions to this estimate. The biggest variable determining how fast equipment can restart, he said, is the frequency of aftershocks, and he pointed out that automotive and specialty-use chips go through customer-specific qualification — the process of confirming a part meets required specifications — before use, meaning they cannot be substituted with output from another fab in the short term (CNA, July 30, 2026; Taipei Times, July 31, 2026). In other words, the "0.03% impact" figure assumes products that can be substituted; it does not apply as-is to automotive or specialty chips.

A companion piece on why semiconductor capacity is so concentrated in Kumamoto in the first place — and which products do or don't have a backup factory elsewhere makes the same point: substitutability varies sharply by site and by product. Set alongside the redundancy assessment from our initial status report on the day of the quake, a structure emerges: JASM itself would normally rank "high" for substitutability, but the constraint of automotive qualification partially cancels out that rating. This isn't something the size of a single number alone can put to rest.

TSMC subsidiary JASM had issued no fourth statement as of the morning of July 31. The state described in its third statement — issued at 8:47 p.m. Taiwan time on July 29, noting that equipment inspection and recalibration was continuing and that full recovery had not been declared — remains unchanged (Taipei Times, TechNews, July 31, 2026). Note also that the seismic intensity actually recorded at JASM's Kikuyo site was 5-upper (per TSMC's own statement), distinct from the intensity 7 recorded in Uki City and Hikawa Town. It's worth reiterating here, too, that a partial restart and full recovery are separate concepts.

[July 31 night update] This section's point — that automotive chips can't be quickly substituted because of customer qualification requirements — was borne out on the night of July 31 in the form of automobiles themselves grinding to a halt. Per Jiji Press (filed 8:02 p.m., July 31), Aisin Kyushu (Kumamoto City) — an automotive-parts maker, not a semiconductor maker — was damaged in the quake and has halted production of key car-door components. This single parts plant's shutdown has now halted Toyota's Tahara plant in Aichi Prefecture from August 3 to 7, and led Toyota Motor Kyushu to further extend the halt at its three Fukuoka plants beyond the period through July 31 originally planned (the report gives no specific end date for the extension). Honda has also extended its Kumamoto plant's halt through August 7, Daihatsu has extended the halt at its two Kyushu plants through August 5, and Nissan has extended a partial halt of some models' production at its two Fukuoka plants (the same report describes this only as "through the same day," so no specific date can be pinned down). Even as recovery at the semiconductor fabs advances, the automotive halts have spread beyond Kumamoto Prefecture. A single irreplaceable part stopping is enough to halt a finished-vehicle line — and that structure isn't limited to chips.

What is the state of ports, seismic activity, and society?

According to the Ministry of Land, Infrastructure, Transport and Tourism's tenth damage report (as of 7:30 a.m., July 31), the container crane at Yatsushiro Port has sustained rail damage and an oil leak, and port operators, the crane manufacturer, and port-construction contractors are on site examining repair options. No recovery timeline has been given yet (Ministry of Land, Infrastructure, Transport and Tourism, July 31, 2026). The same report also confirms that Yatsushiro Port's container quay (12m depth, 200m long) was judged, in the early hours of July 30, fit to berth vessels for emergency transport. But "the quay can be used" and "the crane can be used" are separate matters, and the two should not be conflated.

Aftershock activity is beginning to settle. Per Japan Meteorological Agency figures (as of 5 p.m., July 30), aftershocks of intensity 5-lower or greater totaled just five, and none has occurred since the M5.8 quake at 10:19 p.m. on July 29, through the morning of July 31 (Japan Meteorological Agency, July 30-31, 2026).

The human toll continues to grow. NHK reported, in a flash bulletin as of 9:40 a.m. on July 31, that the death toll had risen to 35, including cases still under review; Kumamoto Nichinichi Shimbun (filed 10:00 a.m. the same day) reported the same figure (NHK flash bulletin; Kumamoto Nichinichi Shimbun, July 31, 2026). [July 31 night update] Per Jiji Press (filed 8:53 p.m., July 31), the death toll rose to 36 on the night of July 31, with more than 9,000 people evacuated. Jiji Press also reported, in a separate article filed at 8:25 p.m. the same day, that resuming Kyushu Shinkansen service between Kumamoto and Shin-Minamata within August now looks difficult.

[Correction, August 1 update] Subsequent primary sources put the death toll at 35 as of 7 a.m. on August 1 (Fire and Disaster Management Agency's 26th report, explicitly noting "unchanged from the previous report"), and Prime Minister Takaichi also stated at the government's disaster response meeting (July 31) that the toll stood at "35 as of 3 p.m. that day." The figure of 36 cited here came from Jiji Press (filed 8:53 p.m., July 31) and has not been confirmed in government primary sources. The latest status is covered in the Day 5 update (Fire and Disaster Management Agency, Prime Minister's Office, August 1, 2026).

In the auto industry, there's no change to the July 29 announcement that Toyota Motor Kyushu's three Fukuoka plants (Miyata, Kokura, Kanda) and Honda's Kumamoto plant would remain halted through July 31. Whether they can restart from August 1 onward was still unconfirmed as of the morning of July 31 (Nikkei, July 29, 2026). Nissan's Kanda plant (Fukuoka Prefecture) has also partially halted operations from the afternoon of July 30 through July 31, owing to damage at parts supplier Aisin Kyushu (Nikkei, July 30, 2026).

Where is market attention focused?

Tokyo's market rose sharply on July 31. The Nikkei average closed its morning session at 64,572.25, up 2,704 points from the previous day, briefly gaining more than 3,400 points. Market commentary cited "chip-stock buybacks" as the driver (Jiji Press, filed 11:41 a.m. and 12:16 p.m., July 31, 2026). This was a broad market-wide rebound, however, and no reporting has confirmed that Kumamoto's recovery progress was the main driver.

Among individual stocks, Renesas Electronics — which had announced the Nishiki plant's restart and the Kawajiri plant's planned August 5 restart the previous evening — was bought up 7.51% to 3,436 yen (as of 1:29 p.m., July 31). No commentary has explicitly tied this rise to recovery progress, though, and as of this writing it cannot be separated from the market-wide chip-stock buyback. Sony Group, meanwhile, moved little, up 0.26% at 3,819 yen (as of 1:28 p.m.), but the company released its Q1 FY2027 earnings on July 31 (revenue up 8.2% year-on-year, operating profit up 40.2%), and earnings appear to be the main driver of its stock move (Yahoo! Finance, July 31, 2026). How the Kumamoto plant's halt was factored into its earnings outlook remains unconfirmed as of this writing.

As for an "extremely severe disaster" designation, no reporting had confirmed a decision or prospect as of the afternoon of July 31. The Prime Minister's Office's chief cabinet secretary press-briefing page had not yet posted anything for July 31 (Prime Minister's Office, checked July 31, 2026). Likewise, no new announcement has been confirmed regarding Toyota's, Honda's, or Nissan's restart prospects from August 1 onward.

[July 31 evening update] At the close, the Nikkei average surged to 64,362.02, up 2,494 points from the previous day (Jiji Press, filed 3:40 p.m., July 31). Chip-related stocks also surged broadly: at the 3:30 p.m. close on July 31, Advantest rose 16.34% (32,500 yen), Disco 12.74% (58,480 yen), Tokyo Electron 6.24% (55,500 yen), Renesas 7.70% (3,442 yen), and SCREEN 5.18% (12,600 yen). Sony Group, by contrast, dipped 0.58% (3,787 yen) (Yahoo! Finance). The main driver cited for the close was reassessment buying of AI and chip stocks following strong earnings from US tech firms, and no commentary has attributed the move mainly to hopes for Kumamoto's earthquake recovery. The center of gravity behind the rally may have shifted from the morning's "chip-stock buybacks" by the close. Neither a decision on the severe-disaster designation nor new restart prospects for Toyota, Honda, or Nissan from August 1 onward had been confirmed as of the evening of July 31.

Key takeaways

• Renesas's Nishiki plant resumed production on the night of July 29, about 30 hours after the earthquake. Sustained cleanroom air conditioning and power kept cleanliness intact, enabling the early restart (Renesas's official second statement, 5:18 p.m., July 30). The Kawajiri plant is scheduled to resume progressively from August 5, but that date is not yet confirmed. Renesas's official third statement (July 31) said the Nishiki plant had returned to pre-earthquake production capacity that morning — the first Kumamoto semiconductor site to reach that milestone. Kawajiri aims to reach pre-earthquake capacity within about three weeks of its August 5 restart (Renesas's official third statement, July 31).
• Sony's Kikuyo plant had given no restart timeline as of the morning of July 31, but its official second statement that evening announced it "plans to resume operations progressively from August 4" and "expects to return to pre-earthquake production levels by mid-August" (Sony official statement; Nikkei, filed 5:00 a.m., July 31).
• A DIGITIMES analyst's estimate found that even in a worst case where JASM halts for a week and recovers none of the lost output, the revenue impact would be limited to about 0.03% (roughly $14 million) of TSMC's Q3 revenue guidance midpoint. This is a third-party estimate, not TSMC's own disclosure, and automotive and specialty chips cannot be substituted in the short term because of customer qualification requirements (CNA, July 30). On the night of July 31, with Aisin Kyushu (Kumamoto City) damaged, the automotive impact spread beyond Kumamoto Prefecture: Toyota's Tahara plant (Aichi) halted August 3-7, Toyota Motor Kyushu's three plants extended their halt, Honda's Kumamoto plant halted through August 7, and Daihatsu Kyushu through August 5 (Jiji Press, filed 8:02 p.m., July 31).
• At the ports, Yatsushiro Port's container crane suffered rail damage and an oil leak, and repair options are under review (Ministry of Land, Infrastructure, Transport and Tourism's tenth report, as of 7:30 a.m., July 31). As of 5 p.m. on July 30, there had been five aftershocks of intensity 5-lower or greater in total, and none since the M5.8 quake at 10:19 p.m. on July 29. Resuming Kyushu Shinkansen service between Kumamoto and Shin-Minamata within August now looks difficult (Jiji Press, filed 8:25 p.m., July 31).
• The death toll rose to 35, including cases still under review (NHK, as of 9:40 a.m., July 31). Toyota's three Kyushu plants and Honda's Kumamoto plant remain halted through July 31 with no change, and Nissan's Kanda plant is also partially halted owing to a parts-supply delay. Tokyo's market on July 31 rebounded sharply — up 2,704 points in the morning session alone — and closed up 2,494 points at 64,362.02, with chip stocks surging across the board (Advantest +16.34%, Disco +12.74%, Tokyo Electron +6.24%). But the main driver was a reassessment following strong US tech earnings, not Kumamoto's recovery progress, and no reporting has drawn that connection (Sony Group ended down 0.58%). On the night of July 31, the death toll rose to 36 with more than 9,000 people evacuated (Jiji Press, filed 8:53 p.m., July 31). Primary sources (Fire and Disaster Management Agency, Prime Minister's Office) put the toll at 35 as of August 1, unchanged from the previous report.