Kazuki attends school posing as Mitsuki Sanada's younger brother. A huge group of male students give him love letters for her and try to buy the lunch she made for him. Annoyed because he accepted all the love letters, Mitsuki makes him write a response to each one. The next day, Mitsuki is upset to learn D is moving in with them. Ken Sanada had put her in Kazuki's room, saying that it will improve morale between the pilots and D responds to Kazuki, so Mitsuki builds a wall to separate D and Kazuki. The gang takes care of some household chores and Mitsuki gets upset when D follows Kazuki's instructions instead of hers. Mitsuki is angry when D accidentally throws her diary away, but tells D it does not matter. D goes off in the rain to search for it and Mitsuki and Kazuki look for her. When Kazuki comes home he finds another door to his room. Mitsuki comes in and they both learn that Yayoi, who lives next door, will be part of their daily routine too.