Ep. 3: Yūya and Mitsuki bond while Yukina and Hiyori create romantic tension and embarrassment.

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Trapped in a bathroom, Yūya shares his shirt with Mitsuki, leading to emotional bonding that partially refills her heart belt. Yukina rescues them and introduces herself as Yūya’s childhood friend, upsetting Mitsuki. Later, Hiyori warns Mitsuki about Yukina’s advances, claiming jealousy drains the heart’s contents. Hiyori possesses Mitsuki to flirt with Yūya, forcing him to admit he likes both large and small breasts, which embarrasses Mitsuki but refills her heart. The next day, an accidental spill reveals Mitsuki’s panties to Yūya. She refuses to walk to school with them, denying Hiyori’s claim that she is jealous. At school, Yūya remains embarrassed by the incident while Mitsuki realizes she forgot to put her washed panties back on. Ayaka invites her to lunch, but Mitsuki declines due to wind. Yukina attempts to help, but a gust exposes Mitsuki’s rear to Yūya, causing him to fall and hit his head. The episode concludes with Mitsuki finding anonymous new panties on her desk, while Yūya suffers from memory loss in the nurse’s office.