Sunas studierende Schwester ist auf Heimatbesuch und ist mehr als nur überrascht zu hören, dass Takeo nun eine Freundin hat …
As word spreads around class about Takeo and Yamato's relationship, Takeo saves a child from drowning on his way to another date. As the pair take a stroll through the park at night, where Takeo appears to miss some subtle hints from Yamato, Suna is visited by his older sister Ai, who is shocked to hear Takeo has a girlfriend, having had a crush on him herself. The next day, Ai brings herself along to Takeo's next date to meet Yamato, who becomes shocked when she learns she messed the cookies she baked. Yamato feels relieved that Takeo likes them anyway, but becomes downhearted when he mentions how pure she is, something Ai is keen to pick up on. Noticing Takeo realise his own denseness and putting in the effort to try and understand Yamato, Ai offers to speak to Yamato about what's bothering her.
La journée commence mal pour Takeo, qui est confronté à quelques soucis de train. Par la suite, Ai, la sœur de Suna, fait son apparition.
砂川の3歳年上の姉・愛が、大学のある名古屋から帰省してきた。愛は猛男に彼女が出来たことを知って大ショック！！実は、愛も猛男のことがずっと好きだったのだ！！「猛男に彼女が出来るはずがない」と疑う愛は、猛男の彼女（すなわち大和）のことを調べるべく、行動を開始するのだった！！
Sem saber o que se passa pela cabeça da sua namorada, o Takeo começa a quebrar a cabeça em busca de respostas.
Justo cuando la historia de amor entre Takeo y Yamato va como un cuento de hadas, aparece alguien que pretende cuestionar e intervenir en su unión. Lo peor de todo es que se trata de alguien relacionado a su mejor amigo Suna.
Ai, la sorella di Sunakawa di tre anni più grande, torna a casa e rimane shockata scoprendo che Takeo ha la ragazza. Nutrendo segretamente da tempo dei sentimenti per Takeo, Ai è sospettosa nei confronti di Yamato e inizia a investigare.
