Masami Shippo is a young woman living in the 2007 setting of the series. She first encounters Gawl while working at a part-time job, initially mistaking him for a local fast-food stalker that has been lurking in the area. Despite this awkward first meeting, she eventually allows Gawl, Koji, and Ryo to stay at her home, where she lives with her mother, who rents out a room to the trio.

Masami’s personality is defined by a quick temper and a strong, independent streak. She constantly argues with Gawl, a pattern that stems from their poor first impression, but beneath the bickering she develops a clear romantic interest in him. She is also fiercely protective of her friends and shows a caring side, particularly toward her best friend Natsume, a shy pink-haired girl who often tries to mediate when Masami and Gawl clash.

Her role in the story is that of an ordinary person drawn into the extraordinary conflict between the time-traveling scientists and the Generators. She provides a link to the everyday world and a home base for the trio. While she has no superhuman abilities herself, her presence grounds the narrative and she becomes emotionally invested in Gawl’s mission, often putting herself in danger to help. Her relationship with Gawl evolves from antagonism to genuine affection, marking her primary character development. She also shares a close friendship with Natsume, which becomes complicated when Natsume is revealed to be working for the antagonist Ryuko Saito. Masami’s loyalty and growing understanding of the stakes around her demonstrate her maturity as the series progresses.