Seishi is a masculine Japanese given name. Notable people with the name include:Seishi Kanetsuki , Japanese jurist Seishi Kikuchi (1902–1974), Japanese physicist Seishi Kishimoto , Japanese manga artist Seishi Yokomizo (1902–1981), Japanese writer Seishi (聖師) Onisaburo Deguchi (出口王仁三郎) (1871–1948), Japanese spiritual leader Seishi Yamaguchi , Japanese haiku writer