Hina Yumihara

In 2014, Hina is shy, especially when Aoba is around, and it is hinted multiple times that she has feelings for him. She also acts very stiff and formal towards Aoba. However, she shows a lot of determination to protect him from an old acquaintance of hers; she came back in time to save Aoba from the that very person. (Source: Buddy Complex Wiki)