Tagami Matajiro

Tagami Matajiro is a 19 year old member of the Shinsengumi introduced in Volume 4, right after Hijikata Toshizo introduces some new troop rules. Tominaga Sei finds them extremely harsh (as anyone found breaking the rules will be sentenced to seppuku), but Tagami quickly pipes up that you aren't a true bushi if you're afraid of seppuku.

Tagami is not a skilled swordsman, but he boasts a big spirit. Sei considers him to be a jerk who is mostly talk; the latter appears to be true after Tagami is struck and injured from behind - a violation of the new rules - and sentenced to seppuku. Nevertheless, Sei argues with Hijikata about the rules, though both he and Okita Souji refuse to budge on the matter. Tagamai, though visibly shaken, appears to have made peace and tries to calm Sei down.

Later that night, Sei sneaks out only to find that Tagami has made a run for it, killing the man who was charged with keeping watch. Though she intends to let him go, Tagamai is stopped by Soji. Though he begs to be spared, he is eventually killed by Sei, who finally understands the meaning of the new rules.