Satsujinki Tantei no Detsuzou Bigaku

Since the death of her sister, police force newbie Yuri Uguisu has been chasing the notoriously untraceable serial killer Masquerade. When a new corpse turns up in Odaiba, Yuri immediately goes on alert—only to recognize the victim as an old classmate, the alluring and mysterious Reina Myoko. When the police force calls in long-time consultant psychologist Seiren Higano for assistance in untangling the testimonies of Reina’s father, fiancé, and lover, Yuri meets the riveting, charismatic psychologist for the first time. Little does she know that Higano is none other than Masquerade himself. Faced with Reina’s case, Higano promises to get the answers, but no one is prepared for the conclusion reached in the interrogation room…
In this cat-and-mouse tale of hunter and hunted, Eiji Mikage has woven a subtle and twisting tale of clashing motives and murky identities, where nothing anyone says can be taken at face value.

[From Kodansha]