Mitsubishi Materials' subsidiaries rewrote inspection data for 800+ customers

On November 24, 2017 Mitsubishi Materials president Akira Takeuchi told reporters that subsidiaries Mitsubishi Cable Industries and Mitsubishi Shindoh had shipped out-of-spec products whose inspection records had been rewritten — at Mitsubishi Cable's Minoshima plant, rubber seal materials (gaskets), and at Shindoh, copper alloy products. The company put the count of possibly non-conforming pieces at some 270 million (full press-conference transcript, THE PAGE).

The investigation committee's interim report (December 28, 2017) found Shindoh had been rewriting inspection data on an organized basis since the 1990s, that three directors knew and never told the board, and that former cable president Murata may have known since around 2013. The motive: avoiding the losses of scrapping non-conforming goods, and share expansion at any cost for a late entrant. Cable crews worked off a list of 'allowable values' that blessed out-of-spec parts.

Instead of closing the file, the company kept widening it. On February 8, 2018 it admitted three more group companies — Mitsubishi Aluminum, its subsidiary Tachika Metal Industry, and auto-parts sinterer Diamet — had also rewritten data, lifting the customer count to about 495; Diamet's parts had gone to Western automakers, and some shipments continued even after the November discovery. The final committee report came out March 28, 2018.

Then the fraud surfaced at the parent itself: on June 8, 2018 Mitsubishi Materials disclosed its Naoshima smelter had shipped non-JIS concrete raw material certified as JIS. On June 11, 2018 President Takeuchi resigned — moving to a chairman post stripped of representative power, with Naoshima's plant chief dismissed. Sankei counted the eventual customer total at over 800.

About 270 million units possibly non-conforming, shipped to 800+ customers including Western automakers; President Takeuchi resigned.

The committee attributed the fraud to a share-first strategy: as a late entrant, losing an order hurt more than bending a spec, so crews shipped borderline and failed lots rather than scrap them.

Rewriting was organized, not rogue: a 'list of allowable values' told inspectors how to pass non-conforming goods, and the practice ran for decades without audit pushback.

Governance failed by design: three Shindoh directors knew and never told the board, and the parent's first internal survey omitted three companies later found cheating.

Disclosure drip-fed: the parent's own smelter was still shipping mislabeled product in June 2018, six months after the first apology, which finally cost the president his job.

Letting inspectors rewrite records to save a shipment is borrowing against reputation. Japan's manufacturers spent 2017 discovering the balance due on decades of those loans.

The final committee report (March 28, 2018) forced leadership changes, and the June 2018 Naoshima disclosure cost Takeuchi the presidency; Naoko Ono took over and JIS certification for the Naoshima product was revoked. Mitsubishi Materials rolled out automated inspection and published recurring reoccurrence-prevention progress reports into 2019 (MONOist). The case sits in the same October-2017 wave as Kobe Steel and Toray — the era when Japan learned that its quality legends had decades of quiet falsification behind them.