Why TSMC Built a Fab in Rural Kumamoto: Water, Sony, and Billions in Subsidies

"Why did the world's number-one chipmaker land in the middle of farmland in Kikuyo?" is the question almost everyone asks first. This article walks through what JASM is, why Kumamoto won the site, what the fab makes, and what has happened to the region since. For the broader story of Japan's semiconductor comeback, see Japan's growth strategy for semiconductors (in Japanese).

What is TSMC's Kumamoto fab (JASM)?

JASM (Japan Advanced Semiconductor Manufacturing) is a subsidiary of Taiwan's TSMC — the world's largest foundry, meaning a company that manufactures chips under contract for others — operating a volume-production fab in the town of Kikuyo, Kumamoto Prefecture. TSMC holds the majority stake, with Sony Semiconductor Solutions, Denso and Toyota as co-investors.

Fab 1 began volume production in 2024. It is widely seen as the symbol of near-leading-edge manufacturing returning to Japan after the country let it slip away decades ago — a significance best understood alongside why TSMC matters so much to the world (in Japanese).

Why did TSMC choose Kumamoto?

There are three big reasons.

First, water. Chipmaking requires washing silicon wafers hundreds of times, which demands enormous volumes of ultrapure water — water refined to an extreme level of cleanliness. Kumamoto sits on abundant groundwater fed by the Aso volcanic range, and that resource met the requirement.

Second, the neighbor. Sony's image-sensor fab — one of JASM's biggest customers — stands immediately next door. Making chips within sight of the customer that uses them is an advantage in both logistics and day-to-day engineering coordination.

Third, the cluster. Kyushu has hosted semiconductor plants since the 1970s and earned the nickname "Silicon Island." The region already had operators who could run a fab floor, supplier firms handling cleaning chemicals and photoresist (the light-sensitive material used to print circuit patterns), and technicians who maintain production tools. A fab is not just a building; it only comes alive with the people and local suppliers who run it. Kumamoto already had that foundation in place.

What does the Kumamoto fab make?

Fab 1 does not make leading-edge smartphone silicon. It makes chips on the 12-28nm generations — the "workhorse" nodes.

The generation number (the process node) describes how fine the circuitry is; smaller means more advanced. While 12-28nm sits several generations behind the leading-edge 2nm, it is the main battleground for the chips used in massive volume across cars, image sensors and industrial equipment. Fab 2, now under construction, is planned to add the finer 6-7nm generations, and total investment across the two fabs exceeds 20 billion dollars.

Whether these chips can be produced reliably depends on yield — the share of good chips per wafer — and on the strength of packaging and materials supply. Japan's outsized role in materials is covered in why chips cannot be made without Japanese materials (in Japanese).

What is happening to Kumamoto?

JASM's arrival changed the region in a remarkably short time.

Employment, capital spending and supplier clustering accelerated at once, and land prices and rents climbed in Kikuyo and the surrounding towns. Engineers and their families are moving in, lifting demand for housing and retail. At the same time, new problems have emerged: commuter congestion, local companies struggling to hire against the fab's wages, and the impact of chipmaking's heavy water use on the region's groundwater. The prefecture is advancing groundwater-conservation measures, but every additional fab raises the stakes on water and power. Light and shadow are advancing together — that is Kumamoto today.

Key takeaways

• JASM is a subsidiary of Taiwan's TSMC (with Sony, Denso and Toyota as investors); its first fab in Kikuyo, Kumamoto began volume production in 2024.
• Kumamoto was chosen for its abundant groundwater, the adjacent Sony fab, and Kyushu's semiconductor talent base — plus massive government subsidies.
• The fab makes workhorse 12-28nm chips, not leading-edge parts. Fab 2 is planned for 6-7nm, with total investment across both fabs above 20 billion dollars.
• The region has gained jobs and investment, but also faces rising land prices, labor shortages and groundwater concerns.
• Kumamoto has become the place where Japan's semiconductor revival is visible on the ground.