The development of Digital Research's fully-compatible MS-DOS competitor, DR DOS, was encouraged when, according to https://retrotechnology.com/dri/dri_wein.html
After DOS Plus for Philips we did a version for Amstrad, but soon it became apparent that we needed a more native implementation of the DOS API to be more compatible, and the opportunity arose when Kay Nishi of ASCII Corporation in Japan put up a million dollars for a contract to develop it after he fell out with Microsoft (he had been instrumental in opening the Japanese OEM market for Microsoft).
The falling out happened March 14, 1986, according to this paywalled article: https://www.wsj.com/articles/SB10001424052748703806304576232724103241208
The tensions finally came to a head in March, the day after Microsoft completed a very successful public offering.
When did Nishi offer, and subsequently award, the million dollar contract for the DOS competitor?