- Setsuna Yatsusaki (八咲 せつな, Yatsusaki Setsuna?)
Voiced by: Kana Hanazawa (visual novel)
Setsuna is a girl in Yūto's class; she is known as "faithful dog Hachikō". She is considerably clumsy. She has been seen by Yūto together with Keiji in Akihabara and at Comiket. Like Keiji, she originally comes from Kyōhaku Dog's. She only cameos in the anime.