Koi Ja Nai No Da! Manga

Koi ja Nai no da! summary:

Because of a strong trauma in the past, Nanno is a coward when it comes to love. When she was a 6th year in elementary school, the boy she loved threw away her love letter. As a result, Nanno thinks she can't love anymore. But she finds she is interested in the boy who joined the same committee as her... However, what will she do when she finds out he is Tsuzuki, the one who caused her trauma!?