Kuze Sōsuke (久世 草介?) is a sumo wrestler from Eigadai Affiliated High School. He is the son of the last Japanese yokozuna, Yamatokuni. Upon entering his father's stable he took the shikona of Kusanagi Sousuke. He holds the rank of Ozeki, and has yet to win a yusho.
District Preliminary arc
Along side Kariya Shun they attend the district preliminary bout between Onimaru and Sada Mizuki. Observing the match they discuss each individual's fighting style and the possible outcome of the match.
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
Sat down backstage away from the tournament's action. Kuze over hears about Kariya Shun's match against Ushio Hinomaru from two people walking past, he stands up and heads towards the match. Observing their match, Kuze is taken by suprise. Backstage afterwards, Kariya claims his sumo isn't wrong and he will win next time. Agreeing with him, Kariya throws a lioncloth at him and asks if he will fight. Kuze confirms he will after a moments silence. Asked by Kariya if he's fighting for his revenge. Kuze declines and mentions he wants to fight in a formal match. When Kariya questions if his blood was stirred up by Ushio, Kuze confirms it. Shortly afterwards, Kuze now dressed for competetion heads to the sumo ring and prepares to face Kunisaki Chihiro.
- 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.