Primary

• Mikaela Hyakuya Best friend of Yuichiro Hyakuya

Extended

• Yuichiro Hyakuya Best friend of Mikaela Hyakuya
• Yuichiro Hyakuya Partner of Shinoa Hiiragi
• Yuichiro Hyakuya Partner of Shihou Kimizuki
• Yuichiro Hyakuya Partner of Mitsuba Sanguu
• Yuichiro Hyakuya Partner of Yoichi Saotome