Sankaku Mado no Sotogawa wa Yoru

Since he can remember, Kousuke Mikado has been able to see ghosts. He wears spectacles in an attempt to hide his ability because he is so afraid of them. He catches the eye of eccentric medium Rihito Hiyakawa one day while working at a bookstore. Hiyakawa is confident that he and the man were meant to meet. Mikado is dragged into the supernatural realm as a result of Hiyakawa's pranks, with the latter pledging to get over his anxieties if Mikado sticks with him. As their collaboration progresses, the two learn about other evil curses that all refer to "Erika Hiura." What are they trying to accomplish, and how are they related to Mikado and Hiyakawa?