Sekine invites Chiyo to a sleepover at her house, and the other two invite themselves as well. They deepen their bond while Rikka learns more about the quirky cultural activities that take place on Earth.

The four friends go on a trip to Atami, a resort area known for its hot springs and traditional wooden dolls. However, it also featured an eagle-eyed local who could accurately determine Tsubasa's gender.