Sendou Ryuudai (千堂 竜大, Sendou Ryuudai; "Ryuudai Sendou") is a member of Ogun Union.
Ryuudai has long, light-colored hair with a bow in it. He also wears a coat with a gradient on it and pants with a flame pattern on the knees.
Ryuudai is overposessive of Ogun Tetsuma, and will defend Ogun Union no matter what. When Kraken suggests that the workload from the hangure was difficult, Ryuudai got very upset. Ryuudai also beats up anyone who he thinks Tetsuma might like more than him.
Ryuudai and Tetsuma have known each other since at least high school. Tetsuma told Ryuudai he liked him, and since then Ryuudai has felt like he can never lose because he doesn't want Tetsuma to stop liking him.
Futaba Jyungo, a middle schooler, defeats Ryuudai in the tournament.
- Ryuudai practices lethwei, a martial art.
- Ogun Tetsuma: Ryuudai is incredibly posessive over Tetsuma, so much so that he will defeat any person that he thinks Tetsuma might like.