Kazuki attends school posing as Mitsuki Sanada's little brother. They give him love letters for her and try to buy the lunch she made for him. Mitsuki is upset he accepted all the love letters and makes him write a response to each one. The next day Mitsuki is upset to learn Dee is moving in with them. Ken Sanada put her in Kazuki's room and he said it will improve morale between the pilots and Dee responds to him. Mitsuki builds a wall to separate Dee and Kazuki.
いよいよ学校に通うことになった僕。けど、三月さんの弟として振る舞わなきゃならなくて精神的疲労は大きい。そんなこんなしているうちにＤまで同居したり、三月さんの日記がなくなったり、さらには弥生さんがとんでもない暴挙に出たり……。一体何だって、この家にはこんなに事件ばっかりおこるんだ!?
El doctor Sanada matricula a Kazuki en el instituto, como hermano de Mitsuki y como Kazuki Sanada. Por otra parte, D se instala en la casa de Sanada para desarrollar sus sentimientos como humanos ...
