The eponymous girl with amnesia and Mari Satou's lover.
Arisa's lover for three years. Tries to cope with her memory loss by being as supportive as she can.
- Bifauxnen: She used to have longer hair in high school, but had since cut it short. Because of this, Arisa and an elderly neighbor initially confuse her for a man.
- Only Sane Woman: Serves as this as a means of dealing with her lover's sudden amnesia.
- The Stoic: Hardly emotes much.
- Not So Stoic: When she's around Arisa, her true feelings always come out.
- Shrinking Violet: She feels that she doesn't deserve a girlfriend like Arisa especially when Arisa accepted that they dated for three years while the opposite would be true if Mari acquired amnesia.