Ookuma Daigorou started out as a student under Katsu Kaishuu, but got kicked out for lacking courage. He ended up at the Kamiya dojo where Kaoru took him on as an apprentice and taught him proper swordsmanship.
He's best known for being serious about his training and developing a close friendship with Yahiko, who picked up on Daigorou's passion for learning and eventually started borrowing science books from him. There's clearly some romantic interest there when it comes to Katsu Itsuko, and he holds Kaishuu in high regard despite being cast out by him.
One of his most prized possessions is a Jules Verne book that Kaishuu gave him—supposedly telling him it was essential reading for anyone serious about exploring the world of science. He keeps it close as a reminder of that connection.
Content compiled by AnimeList.moe from publicly available sources.
