Sakamoto-san runs a pet shop where the protagonist purchases a kappa. She holds deep expertise in kappa care, regularly advising customers on their upbringing, dietary needs, and behavioral management. Her guidance proves essential for overcoming kappa-raising challenges, including swimming instruction and health issues such as sun exposure. Adopting a pragmatic and business-focused attitude, Sakamoto-san consistently markets kappa-related merchandise during consultations, turning advice sessions into sales opportunities. She cares for Kyuu, a kappa with a cracked shell housed at her shop, and orchestrates Kyuu's budding friendship with the protagonist's kappa.