Hase Seishū (馳 星周, born February 18, 1965) is a well-known Japanese novelist. He is known for writing Yakuza crime novels.
He was born in Hokkaido, Japan and graduated from Yokohama City University with his B.A. in 1987.
A few of his novels were adapted into Asian films, such as The City of Lost Souls and Sleepless Town, in 2000 and 1998, respectively.
Seishu also wrote the story for Sega's 2005 video game, Yakuza, and its 2006 sequel, Yakuza 2. He had no involvement with later entries in the series.