Daigorou Ookuma

Ookuma Daigorou is student of Katsu Itsuko's father Katsu Kaishuu who disowned him as student because he was cowardly. Kaoru Kamiya took him as an apprentice at the Kamiya dojo where Daigorou learns swordsmanship from Kaoru.

He makes friends with Yahiko who is fond of Daigorou's studies and later on even starts reading science books lended from Daigorou. It seems he has romantic feelings for Katsu Itsuko and highly respect Katsu Kaishuu.

One of his personal treasures is a book by Jules Verne given to him by Katsu Kaishu who said it is a must for someone who wants to explore science.

(Source: Rurouni Kenshin Wikia)