Shortly after winning the World Martial Arts Tournament and using the prize money to settle her grandfather's one hundred million yen debt, a reporter arrives at Kizuna Todoroki's home. Impressed that such a young girl managed to defeat the champion who had held the title for ten years, the reporter wants to interview Kizuna for an article about her and the Wadachi Ju-ken school of martial arts founded by Kizuna's grandfather. However, before the interview can conclude, challengers start appearing at the Todoroki residence. After learning that Kizuna is only 12, they hope to defeat her before her 13th birthday to take over her position as world champion. As dozens of challengers show up, Kizuna struggles to defeat them all, while the reporter learns more about the Todoroki family.