No release date, platform or region has been announced yet. Source: Official announcement
The anime Bless has released a character PV for MM and announced that Kentaro Kumagai will voice the character. The video, "Character PV MM ver.," is the first to let viewers hear MM’s voice.
Kumagai also sent a comment. He first met the work as a reader, and still vividly remembers the shock of turning the page at one particular scene, which gave him goosebumps. He said he is truly glad to have been given the role, and that he will give his all to MM, a member of Mirror who is more grown-up than those around him.
announced by the official ‘Bless’ website
Official source: bless-anime.com