What a weird thing this is.
https://www.animenewsnetwork.com/news/2018-02-01/one-punch-man-artist-yuusuke-murata-to-launch-manga-based-on-back-to-the-future-film/.127228 (https://www.animenewsnetwork.com/news/2018-02-01/one-punch-man-artist-yuusuke-murata-to-launch-manga-based-on-back-to-the-future-film/.127228)
Well it's dead. I was kind of looking forward to it too.
https://www.animenewsnetwork.com/news/2018-09-16/back-to-the-future-manga-by-one-punch-man-artist-yuusuke-murata-cancelled/.136854
Ah blissful goodnight to BttF manga efforts I suppose they have other things to work on anyway