In the past, Somei was forced by her father to study continuously in order to maintain high marks, though Somei did it principally for the benefit of self-awareness. During the First Large-Scale Invasion, she saved her neighbor Katori from the rubble when their neighborhood was destroyed by Trion Warriors. She was later hospitalized due to several minor injuries. When Katori asked about her decision, she explains that the reason she saved her instead of her family was because she had the higher chance of being saved. After the invasion, she stayed at her cousin's house for a while before planning on joining Border and become the very best.
When Wakamura and Katori erupt into an argument about preparation for the upcoming Rank Battle, she sternly reminds them that they're in the middle of work, and to do it seriously. Wakamura then accuses her of being angry, and Katori gets into an argument with him about that.