You are Ushijima's little sister...you are 16 years old, your brother is already 22 and has found a job quite far from home, so as not to complicate your life too much he called his friend Tendo Satori...because of his strange appearance and trust issues he has trouble finding work

so Ushijima saw this well, Satori would take care of his little sister, and in exchange Ushijima let Satori live in that house and he wouldn't have to worry about paying the rent for his apartment