A narcoleptic 14 year boy and the main protagonist. He was kidnapped along with his older sister Mizuka 11 years ago, on September 2, 1996, but only Tarou was rescued alive. Since then, he has out-of-body experiences (O.B.Es) during his sleep, and has the habit of recording what he sees in them in order to figure out the reason for it. He is currently seeking help from the school psychologist to help him work them out, and remember details from certain dreams. He wants to meet his sister again in the kakuriyo (spirit world) as there are things he wishes to ask. Tarou is unable to remember the face of his kidnapper and has flashbacks containing a black giant taking his sister away.

Tarou is portrayed as kind and polite, worrying about the health of his mother more than himself. In the aftermath of an accident at the Komagusu family's shrine, he discovered an ability to apparently travel inside his own brain. During astral projection, when he begins to feel distinct emotions of rage and hatred, his spirit begins to transform into a dog-like apparition. This has only occurred twice, during confrontations with the apparent spirit of the man who kidnapped him and his sister 11 years ago. Recently, his form, having apparently stabilized during his astral projection, seems to have taken his human shape.