Video Gameplay - https://youtu.be/-iPRMg07DxM

Guessing the devs were big fans of Beyond the Boundary. Dude in the first screenshot is a dead ringer for Akihito Kanbara. Also, reading the description of one of the protag's love interests, "...the descendant of a serpent god and a human woman...", pretty much sealed it: Akihito is half-youmu.