Synopsis[]
At the start of her second summer on Aqua, Akari receives a mysterious invitation that directs her to a hidden bay, where she meets Aika and Alice following similar invitations. There they find Alicia and Akira, who sent the invitations at President Aria's instruction, and together they spend a relaxing day swimming in the ocean, which Akari could not do back on Manhome.
While shopping for a noctilucent windchime on a day hot enough for mirages to appear on the ocean, Akari feels dizzy and sees the market as empty of people. She follows President Aria to a cool cafe that serves only ice-cold milk because it is a refuge for the city's cats, where humans don't belong. Cait Sith gives her a cat-shaped windchime, and when she leaves, the cafe turns into a boarded up building and the people return.
Akari meets Woody, a sylph (airborne deliveryman) with a bad sense of direction who has lost his map. She offers to guide him to his destination, and he takes her on a wild "swim" through the streets culminating in a view of Neo-Venezia from the sky.
Akari, Aika, and Alice visit "Grandma" Akino, once the best undine of Neo-Venezia and founder of Aria Company, now in retirement in the countryside. When Aika asks for advice, Grandma has the trainees help with domestic chores, which Aika interprets as tests that will make them better undines. That night, Grandma reveals that the secret to becoming a good undine is to enjoy every moment.
Akari, Aika, and Alice are assigned a charter boat for Redentore, the end-of-summer thanksgiving festival, as a live exercise in hospitality. The evening is successful, and their guests thank them for bringing them together.