"Hachijou Tooya" is Ushiromiya Battler following the murders on Rokkenjima, who lost his original memories by way of nearly drowning in an attempt to save Sayo Yasuda. He was later found by Hachijou Ikuko on the side of the road, and was able to bond with her over their love of mystery novels. Ikuko gave him his new name due to how he was eighteen (十, tō, ten, and 八, ya, eight) years old upon being found.

After learning of Yasu's original forgeries from Ikuko, Tooya became unable to accept his original identity; due to both being the cause of painful headaches, and because Tooya became scared at the thought at having somebody else's memories. To cope with his past existence, he collaborated with Ikuko (who served as a ghost writer) to recreate the events of 1986 based on the forgeries; resulting in the framing device for most of Umineko itself.