Nanaka acts coldly towards Sana the following day, even after Sana explains his incident with Asami was an accident. After Sana exclaims that Nanaka is not her old self, she angrily runs away. Sana comes upon an old mailbox that Sana and Nanaka used for private communication in their youth, and finds dozens of letters, some desperate cries for help. Sana then learns from Syusuke that three years prior, Nanaka's house had burned down, killing both of her parents and traumatizing her. After learning of Yuzuki's ability to cheer herself up with caramel, Sana meets Nanaka, who tearfully denounces him for not being there for her when she needed him most.
朝から機嫌の悪い菜々香と口喧嘩をした佐菜は、菜々香が今みたいに変わってしまった理由に思いを巡らせる。そして、幼い頃は、いつも一緒だった二人の思い出を記憶の中でたどるうちに、昔、菜々香と使っていた“秘密のポスト”の存在を思い出す。懐かしさに駆られて、佐菜は久しぶりに、そのポストを見に行くのだが・・・。
