Main character encounters an aggressive youkai one day. He is saved by the girl Chaime who confronts the monster. The young people join forces since protagonist has an ability to find youkai. The main goal of Chaime is to enter youkai realm and rescue her brother.
They manage to rescue another inspired girl from the attack of youkai, so the plan to kidnap inspired humans becomes evident.
Eventually protagonist gets into youkai prison and meets Chaime's brother, but the grand scale of monsters plan becomes clear now...

[From vndbreview]