As summer arrives, the girls go to the swimming pool to teach Tamako how to swim while Dera learns of Mochizō's crush on Tamako. Dera decides to accompany Mochizō as he and the others go on a school trip to the beach and help him with his love troubles. When Midori learns of this, she chooses to stand against him, although the heat between them soon calms down by the next day as the gang watch some fireworks.