Akino Ametsuchi

A famous and longest-serving Prima undine, who started Aria company with Aria Pokoteng after realizing she was missing too much of life as Himeya's top ace. She was Prima undine for 30 years and mentor to Alicia, her last disciple, to whom she left the company on her retirement. She is highly respected by young undines, especially Alice. She's currently living in the countryside, doing some farming on the side, and will sometimes drop by Aria company with some of the byproducts from her fields. Before she took on Alicia as a student, Akino had another undine named Anna as a student. However, Anna eventually fell in love with one of her customers, married him and moved to Burano Island.

(Source: Wikipedia)