Sen has red eyes and silver hair, which is usually kept so the sides stand out more. She is usually dressed in her school clothes even during the bento brawls and black boots.
A second year student who is the president of the Half Priced Food Lovers Club. Her skill in bento brawls has led her to be known as The Ice Witch. Her title comes from her accidentally almost buying a beer called Ice Cold (氷結 Hyōketsu) because she liked the design and assumed it was a normal drink. While usually calm, she's very innocent and does not particularly know a lot outside of bento brawls and can sometimes be pretty clumsy. She can be very stubborn as well, especially when it involves a challenge from another bento brawler.
Other than bento brawling, she seems to enjoy reading magazines, as she has several of them in her room. However, when she reads out loud, she reads in a monotonous tone. She also has experience in knitting, as she sewed Yō's pants back together. She is exceptional at board games and wins several times in a row against Yo and Hana, although she is rather poor at video games, to the point where she gets angry enough at her losses to throw Yo's console out the window.
She gets along nicely with all but those who disrespects bento brawls the most notable is with Satou Yoh who at first she treats as a mere disciple and underclassmen, but she eventually begins to trust him to the point where he is one of her closest friends.