Asahi Kasei Construction Materials faked pile records — a Yokohama condo tilted

In 2014 buyers at Park City LaLa Yokohama, a four-tower Mitsui-group condo in Tsuzuki ward, noticed one tower leaning. The eventual chain led to Asahi Kasei Construction Materials, the pile-work subcontractor: it had neither kept proper records nor driven every pile to the bearing strata, and its construction reports contained data that had been copied from other jobs and rewritten (Nikkei, Jiji).

On November 14, 2015 Asahi Kasei admitted the falsification and launched an investigation committee, committing its subsidiary to bear the full cost of reinforcing the tilted building and re-surveying the others. The Ministry of Land, Infrastructure and Transport ordered disclosure of pile data across Asahi Kasei Construction Materials' work nationwide, and on December 25, 2015 its countermeasure committee issued an interim report on the systemic rot in foundation-pile supervision.

The external committee — three lawyers chaired by Kazuhiro Suzuki, a former superintendent prosecutor — reported on January 8, 2016 that there had been no procedure for what to do when pile data could not be obtained, and that site-staff training was inadequate; it was criticized for never addressing whether management was responsible. The answer came on February 9, 2016, when Asahi Kasei president Toshio Asano, managing director Hirai and subsidiary president Maeda resigned.

MLIT administratively punished the three companies. The towers were rebuilt (completed 2021), and the billing stayed alive: Mitsui Fudosan Residential sued the three builders for about ¥50.5 billion, and in June 2026 the Tokyo District Court called a full rebuild 'excessive' and awarded only ~¥1.4 billion in repair costs — a verdict Mitsui is appealing.

Mitsui Fudosan sued for ~¥50.5B; in June 2026 the Tokyo District Court awarded only ~¥1.4B. Asahi Kasei's president, a VP and the subsidiary CEO resigned.

Pile work was subcontracted with no independent supervision — MLIT's committee called it 'marunage' (thrown over the wall), so the specialist crew effectively graded its own work.

No procedure existed for piles that yielded unusable data, so workers copied and edited old records; the external committee found no management control that would have caught it.

Main contractor and developer accepted paperwork at face value; nobody re-verified the bearing-strata data on a signature building until residents saw it tilt.

The external committee's scope skipped management responsibility, pushing the reckoning upward: outside criticism forced the president out anyway.

Subcontracting safety-critical work does not subcontract accountability. When the crew writes its own record, 'no data' becomes 'reuse old data' — until physics checks the paperwork.

MLIT punished the three companies in January 2016 and issued new pile-supervision guidelines. The four towers were rebuilt by 2021. Mitsui Fudosan then sued its contractors for ~¥50.5B; on June 17, 2026 the Tokyo District Court ordered only ~¥1.4B, ruling full rebuild 'excessive' and faulting Mitsui for sticking to it after experts said the building would not collapse. Mitsui appealed. The case became the reference point of Japan's 2015 construction-data-fraud wave.