Hiromatsu was a minor hero from the Shōgun novel and television mini-series by James Clavell.
Also known as the Iron Fist, Hiromatsu was one of Lord Yoshi Toranaga's most trusted aides and advisers. Hiromatsu was one of Toranaga's key Generals.
When John Blackthorne arrived in Japan on board the Dutch ship Erasmus in the spring of 1600 word of the arrival got back to Toranaga. Seeing an opportunity to learn more about the Europeans, Toranaga sent Hiromatsu to take charge of Blackthorne and his crew before Lord Kasigi Yabu and Father Sebastio could have them all killed.
After an attempted assassination of Blackthorne it was Hiromatsu who identified the assassin as a member of the Amida Tong.
Later when Toranaga needed to make his escape from Osaka, Hiromatsu was left behind to deliver Toranaga's resignation from the council of regents to Toranaga's rival Ishido Kazunari.
When Yabu's betrayal of Toranaga and his allies was revealed, he was ordered to commit seppuku. Hiromatsu served as Yabu's kaishakunin, or second during the ceremony. After Yabu had disembowelled himself Hiromatsu delivered the killing blow, severing Yabu's head.
Hiromatsu continued serving Toranaga in the battles that saw Ishido defeated and his friend and ally Toranaga named Shōgun.