Hotaro is torn between continuing with his "gray" life and the "rosy" life that the others live. A phone call from Hotaro's sister leads him to believe that there are pieces missing to his theory regarding the events of Sekitani's expulsion.

Hotaro's sister returns home, and sets her lethargic brother up with a temporary job filling in as a lifeguard at the city pool. Satoshi invites Eru and Mayaka out to see Hotaro at work, and the group stumble upon a minor mystery to be solved.