Azusa B. McLaren is a Single (journeyman undine) apprenticed to Aika S. Granzchesta at Himeya Company. Brave, direct, and self-confident, she acts impulsively and without hesitation when intrigued. Azusa meticulously records important information in an electronic organizer.

As a newer generation undine trainee in Neo-Venezia, she forms a close friendship with Anya Dostoyevskaya of Orange Planet. Their regular joint practice sessions forge a professional camaraderie mirroring bonds shared by senior undines, central to her interactions.

During "Aria the Avvenire," an Acqua Alta event cancels duties. Azusa proactively collaborates with Ai and Anya to organize an impromptu gathering for their seniors—Akari, Aika, and Alice—showcasing her integration into the undine community. This gathering coincides with Athena Glory's musical performance, allowing everyone to unexpectedly enjoy the event together.

Her presence signifies the continuation of the undine tradition, embodying mentorship succession and the perpetuation of Neo-Venezia's values through the new generation. Designed by original manga creator Kozue Amano specifically for "Avvenire," Azusa represents ongoing growth within the series' universe; her background prior to becoming a Single remains unspecified.