Relatives: Georgie Saikawa (older sister)

Riko Saikawa is Kanna's friend and classmate in elementary school. A running gag involves her becoming overwhelmingly flushed with bliss every time she and Kanna make physical contact, along with her shiny forehead.

At first glance, Riko seems bossy and mean, but over time, she seems nicer as shown with Kanna, and very polite around people like Kobayashi, although she originally mistook Kobayashi for Kanna's mother. She has a crush on Kanna and enjoys being around her. When being touched by Kanna or when she receives praise from her, she tends to grin goofily and get red in the face, becoming overwhelmed with excitement.

Though she initially tries to pick a fight with Kanna for her sudden popularity on the first day of her transfer to the school, she quickly becomes good friends with her. They often spend time with each other, walking home together from school and picking the other as their partner during school activities.