Let's Put On Our Swimsuits!.Now that it's summer, Asahi gets up the nerve to invite Yoko to the pool. The problem is, Yoko doesn't know how to swim and thinks that Asahi is asking her so they both could practice. To Asahi's consternation, Yoko invites both Nagisa and Shiho to join them, and Asahi's three friends wind up going too. Shiho leads the swimming lesson, with Nagisa as her assistant, but her perverted instructions get Shimada into big trouble. Her next set of instructions cause Nagisa to knock her out and take her place as instructor (naturally in a militaristic manner!), but her teaching style nearly drowns both Yoko and Asahi! Mikan then shows up with her two little brothers (and without her camera for once!) and for the first time shows a softer side when talking about Asahi. After the pool closes and everyone is on their way home, Asahi and Yoko both make excuses and ditch the gang, meeting at the school that evening; it turns out that Yoko wants to continue her swimming lessons at the school pool. After some more practice, Yoko tells Asahi about how her parents learned to swim and how her life has changed for the better since she and Asahi met, but things take an embarrassing turn when they begin to address each other by their first names for the very first time (secretly watched by Akane)!