Seijuro Hiko, whose real name (which is never revealed) is Niitsu Kakunoshin, is the thirteenth successor of the Hiten Mitsurugi style of swordsmenship. Seijuro Hiko (the first) founded the Hiten Mitsurugi style and the name Seijuro Hiko is passed down to each successor of the style who has completely mastered it.

Hiko was Kenshin's master throughout his youth, and essentially his father figure, although Kenshin wasn't the type to look up to anyone back then: just learn and respect from his peers.

Hiko has always, and as far as anyone knows, lived in the mountain ranges near Kyoto in seclusion. He makes income as a potter so that he may purchase his supplies and goods. Hiko has no friends, and the only one he really communicated with besides his master was Kenshin, his pupil.

Hiko trained Kenshin from his youth until he was 14, when he decided to leave their recluse and fight in the name of the people who were suffering in the Bakufu alliance. This was seemingly the last Hiko and Kenshin were ever to speak to one another. Hiko, sending his pupil off to the bloodsoaked fray, and Kenshin never looking back. Hiko remains in recluse to this day only traveling to cities to sell his pottery.