In his first tournament of fourth year Elementary school, he heavily injured his opponent Kariya Shun. From then on he wasn't allowed to appear on the stage of Elementary and Middle school sumo.Cite error: Closing </ref> missing for <ref> tag.
When Onimaru is declared the winner of the match, Kuze becomes surprised and wonders how much he trained to achieve his Hyaki Nagi move.
Later on, Kuze visits the medical room. Upon entering he knocks over Ushio until picking him up and mentioning he's heavier than he had thought.
Placing him down he asks if he's hurt anywhere. When Ushio mentions about him not taking part in matches. Kuze informs him that he doesn't compete until being irrupted by Kariya calling him. When Kuze calls him over Kariya notices who he's talking with and tells him not to waste his time with people who couldn't win the District Preliminary. Kuze mentions he doesn't mean it and he was moved by Ushio's match. When Kariya is told to stop acting cool when they weren't picked to compete at their own District Preliminary. Panicking he says his and Kuze's names will echo in the entire country.
Kanto Newcomer Tournament arc
- Kuze Sōsuke vs Kunisaki Chihiro (Kanto Newcomer Tournament)
- Kuze Sōsuke vs Kinoshita (Kanto Newcomer Tournament)
- Kuze Sōsuke vs Gojō Yūma (Kanto Newcomer Tournament)
- Kuze Sōsuke vs Ushio Hinomaru (Kanto Newcomer Tournament)
- Kuze Sōsuke vs Tennōji Shidō
- Kuze Sōsuke vs Ushio Hinomaru
- Kuze Sōsuke vs Jinou
- His epithet, Kusanagi no Tsurugi, comes from the sword of same name which is one of three Imperial Regalia of Japan.