After helping out at Kino's beach house during a lunch rush, Futaba decides to return there the next day while Hikari goes scuba diving with the others. While there, Hikari accidentally goes into an outdoor hot spring without her bikini top, putting her at risk of being exposed before the other girls come to save her. Later, after Hikari holds a barbecue party for everyone, Futaba worries about what she'd do if she has to part ways with Hikari, but Hikari encourages her to enjoy every moment they spend together.

It's finally time for Teko's advanced certification test, with a promise of a night-diving celebration if she passes!