Primary

• Satoshi Tainaka Friend of Satoshi's Friend
• Satoshi Tainaka Younger Brother of Ritsu Tainaka

Extended

• Ritsu Tainaka Younger Sister of Satoshi Tainaka
• Ritsu Tainaka Friend of Yui Hirasawa
• Ritsu Tainaka Friend of Tsumugi Kotobuki
• Ritsu Tainaka Friend of Azusa Nakano
• Ritsu Tainaka Friend of Mio Akiyama
• Ritsu Tainaka Student of Sawako Yamanaka
• Satoshi's Friend Friend of Satoshi Tainaka