Sankaku Mado no Sotogawa wa Yoru

Synopsis

As Mikado confronts Sensei, his birth father, he learns that Sensei is a killer and hates Mikado himself enough to want to kill him. Despair threatens to make Mikado's powers run wild.
To keep Mikado from going berserk, Erika borrows Hanzawa's power and creates a path to the space that holds Mikado and Sensei. At the same time, in order to save Hiyakawa, Mukae continues to speak with the young Hiyakawa who has fled into a space Sensei has created.

(Source: Crunchyroll)