Primary

• Serenity Wheeler Younger Sister of Katsuya Jonouchi

Extended

• Katsuya Jonouchi Older Brother of Serenity Wheeler
• Katsuya Jonouchi Friend of Mai Kujaki
• Katsuya Jonouchi Best friend of Yuugi Mutou
• Katsuya Jonouchi Friend of Hiroto Honda
• Katsuya Jonouchi Friend of Anzu Mazaki