さんかく窓の外側は夜 / The Night Beyond the Tricornered Window Series by Tomoko Yamashita

Shy bookstore clerk Kosuke Mikado has the ability to see ghosts and spirits, an ability he wishes he didn’t have, since what he sees usually terrifies him. Rihito Hiyakawa, an exorcist whose supernatural powers are as strong as his social graces are weak, doesn’t seem to fear anything, mortal or otherwise. When this odd couple gets together to solve the bizarre cases that come their way, their work methods may not be entirely safe for work!

When exorcist Hiyakawa and his assistant, Mikado, discover the remains of a curse at a murder scene, the only clue they have to the caster’s identity is the name “Erika Hiura.” Later, while investigating an incident at a girls’ school, they finally come face-to-face with their mysterious quarry... moreWhen exorcist Hiyakawa and his assistant, Mikado, discover the remains of a curse at a murder scene, the only clue they have to the caster’s identity is the name “Erika Hiura.” Later, while investigating an incident at a girls’ school, they finally come face-to-face with their mysterious quarry. Although Hiyakawa is stunned to find that Erika is just a high-school student, he’s even more disturbed by the instant, powerful attraction felt between Erika and Mikado—a bond he’s determined to break, at any cost. less

Erika Hiura leads a strange double life as both a normal high school student and a secretly powerful necromancer whose services are sold to the highest bidder. Her interest in exorcist odd couple Hiyakawa and Mikado seems innocent, but when they’re called in to investigate a missing-persons case, the connections between the three may be deeper than any of them realize. Meanwhile, the relationship between Hiyakawa and Mikado continues to evolve in ever more intimate, and disturbing, directions.

When Detective Hiroki Hanzawa confronts necromancer Erika Hiura, it’s Hanzawa’s wife who ends up paying the cost. But Erika herself is badly shaken by their encounter, and after years of cursing others with little thought, she’s beginning to question the results of her actions. At the same time, Rihito Hiyakawa’s seemingly impenetrable self-possession is also starting to crack, and the catalyst behind it all is…Kosuke Mikado.

Rihito Hiyakawa has a tendency to chase after money, and he isn’t too picky about the means or morals of doing so. His partner, Kosuke Mikado, acts as the voice of conscience, the self-designated worrier in the relationship who wants to take care of Hiyakawa and their friends. Each of the men has his own reasons for making the decision to help fellow exorcist Erika Hiura free herself from the sinister cult led by "the Professor," a mysterious figure tied to a string of horrific curses.

A cryptic message from fellow exorcist Erika Hiura arrives at Hiyakawa and Mikado’s office. The team works together to discover the true identity of the Professor, but Hiyakawa has other, less upstanding ideas. When Mikado points out the crudeness of it all, Hiyakawa pushes him away, right into a cursed pond!