Sanpei Nowaki attends Takanoha High School as a student. He is immediately recognizable by his completely bald head and brown eyes. Nowaki harbors an intense, unwavering admiration for fellow student Saki Asamiya, whom he reverently calls "his goddess." This devotion manifests as persistent following, as he shadows Saki across the school campus.

His distinctive baldness stems from a deliberate choice. Nowaki originally possessed long hair but shaved his head entirely upon learning of Saki's dislike for boys with long hairstyles. This drastic act demonstrates his willingness to transform his appearance solely to align with Saki's preferences.

Throughout his interactions, Nowaki remains utterly unaware of Saki's secret identity and activities as the "Sukeban Deka." Primarily, his role provides comic relief through his oblivious yet earnestly persistent attempts to gain Saki's attention. The character appears exclusively within the manga and its 1991 OVA adaptation; he features in no live-action television series, films, or later spin-off productions. Details concerning his family history or personal life beyond his school activities and singular fixation on Saki remain unexplored.