Hailing from Manhome, formerly known as Earth, Ai Aino initially approached Aqua with skepticism, dismissing its tranquil pace as tedious compared to her elder sister’s glowing accounts. Her outlook transformed after befriending Akari Mizunashi, who became her pen pal and shared vivid emails extolling Neo-Venezia’s allure and simple joys. This correspondence ignited Ai’s profound affection for Aqua, leading to repeated visits alongside family members.

As Akari rose to Prima status, Ai joined Aria Company as her apprentice Undine. She trained jointly with peers Azusa and Anya from rival gondola firms, mastering canal navigation and absorbing wisdom from senior Undines through daily drills.

During a prolonged Neo-Venezia winter, Ai accompanied Azusa and Anya to the Undine Museum under Akira’s supervision. There, they met Asuka—the museum director and Akira’s Himeya Company senior. This immersion in Undine heritage deepened Ai’s understanding of her profession’s legacy, anchoring her apprenticeship in tradition.