Arcana (stylized in all caps) is a Japanese manga series written and illustrated by Yua Kotegawa [ja].

He and his partner, Nakabayashi, learn that a doctor from a mental institution called on behalf of one of his patients about the explosion minutes before the bomb went off.

This leads to Murakami's meeting with the nameless and amnesic patient whom they would eventually call "Maki", who appears to communicate with deceased spirits of the dead that tell her things which no living human would know.

Murakami tries to uncover the secret behind Maki as she helps him and Nakabayashi to deal with a series of supernatural crimes committed by a mass murderer.

However, as Murakami finds himself falling in love, he learns of Maki's true nature and her connection to an identical woman named Satsuki.