Warin is a sea dweller who lives underwater alongside her friends Marin, Urin, and Sam, sharing a life entirely beneath the waves where she is especially close to Marin.

When Marin and Urin journey to the human world and fail to return, Warin grows deeply concerned for their safety. Sensing the dark forces of the evil entity Sedna, she fears the worst. Driven by worry, she ventures to the human world to search for and rescue her friends, accompanied by Sam.

Warin holds a strong distrust of humans and is immediately suspicious of their intentions. She becomes convinced that Kanon, the human girl encountered by Marin and Urin, means to harm Marin. Despite these suspicions, she follows Marin and Kanon into a cave on Kagerou Island, where she and Sam eventually find them.

She is skilled in combat, particularly with polearms such as tridents and spears, which she wields effectively for her own defense.