A Japanese Samurai who came to spain as guard of heir of the head of delegation, Hasekura Tsunega. From the first time Maria saw him, she couldn't help but think how handsome he is. Later, she came to like him after he saved her brother. For some reason, some wanted him dead. So he was almost killed, but Maria found him and brought him home and saved his life.
The one wanted him dead is his own twin brother.
The name "Kojirou" was orignally his little brother's name, who died at young age.