It's finally summer - the perfect opportunity to go outside and have some fun! Taking advantage of the good weather is the enormously wealthy Nagi Sanzenin, who invites some friends to a private beach. However, while Hayate, Maria and the others are out enjoying the sun, Nagi chooses to stay inside by herself. Can Hayate persuade her to don a swimsuit and join in the fun, or is there some deeper reason behind Nagi's refusal to go outside?