Nothing much is really known about Matsushima's past except when the outbreak occured she and Asami gathered survivors and made the mall a safe heaven. Matsushima then left Asami in charge and left to check on the police station to get some back-up.
Matsushima was bitten at some point and returned as one of "them" outside the mall which crushed Asami's spirit and made her lose hope.
- Matsushima's gender was not revealed until you saw her as one of "them"
- She appears at the end of the first season leaving the mall after the credits
- Asami had a high amount of resepect for her sempai and was clearly crushed by her death.