The Story of the First Time at Sea With Friends - S1.E5

Noticing Futaba struggling with strength, Mato has her and Hikari go jogging to build up strength. Along the way, they come across some students from diving school, Ai and Makoto Ninomiya, who turn out to be their upperclassmen in the Diving Club. After a hectic first meeting, Ai holds a meeting to discuss how Futaba will be aiming for an Open Water Diver Certification, which somehow ends in a chalk drawing session.