It was released on ASSEMbler (https://assemblergames.com/threads/so-far-undumped-prote-pruste-%E3%83%97%E3%83%AD%E3%83%88%E3%83%97%E3%83%A9%E3%82%B9%E3%83%88-sharp-x68000-xdf-upload.69262/) by Uroko Sakanabito two months ago. I totally missed it!
I've heard that it was sitting on an Oh! X cover CD this whole time and nobody thought to look. D'oh!