Forgot a Manga

[TetraVentus]

I read this manga like a year ago where the MC can create yin/yang portals as his power. His dad/mentor has the same thing but one of his portals is on the bottom of the ocean or something so he essentially has water powers. I don't remember why but this guy like joins a group of monsters so then his dad/ menor gets like hunted down. He and the monsters like go to take over this old lady's place (onsen I think) but she just lets them help it if they agree to staff it. IIRC there's some monster girl character who has a mouth on her stomach and can like use it to eat things.

Please someone help me I have been looking on advanced search for like three hours 😭