Usui, known as the Blind Sword, was once a swordsman serving the shogunate government. However, during a battle with Shishio Makoto, he lost his sight. Despite this, he developed an extraordinary ability called Shingan (Eye of Heart), which is essentially superhuman hearing that allows him to perceive others by listening to their heartbeats and sensing their emotions. This skill is so refined that it resembles the echolocation abilities of dolphins or bats.
Upon joining the Juppongatana, Usui and Shishio made a pact: Usui could attempt to kill Shishio whenever he found an opportunity. Saito observed that deep down, Usui is aware he cannot defeat Shishio and boasts about killing him to mask this weakness from others. Saito also noted that Shishio is fully aware of this and merely plays along to exploit Usui. Unable to challenge Shishio, Usui compensates by defeating weaker opponents to bolster his ego. According to Cho, Usui ranks as the second strongest member of the Juppongatana.
Usui's fighting style involves using a short spear called a rochin, which has a weighted end for striking, and a tortoise shell named a tinbei, which serves as both a shield to deflect attacks and a tool to obscure the enemy's vision.
