The Human Weapon had become a member of Enishi's Jinchuu because he wanted to avenge the death of his friend Nakajou, who he had nightly killing sprees with. Trickery is Hyouko's best game; his tactics in combat do not rely on brute strength. However, if his opponent happens to learn the game being played at hand, defeat is inevitable for Hyouko, as was the result when he had faced Yahiko. It was Hyouko that personally attacked Chief Uramura's residence and left the chief out of commission for a while. Like Saitou, Hyouko has the habit of smoking; not cigarettes, but hookahs.

Hyouko dubbed himself with the name "Human Weapon" due to the number of various weapons hidden in and on his outfit, 13 in all. His weapon of choice is the Bishamonken, an iron sword that works in cohesion with the Bishamonpun, iron powder. For this trick to work, Hyouko breaks a bottle filled with the Bishamonpun in it, covering his opponent in the powder, allowing the Bishamonken to home in and attack at a rather quick speed for one unskilled in sword combat. The Baika Chuuzen is located on his left wrist. It is a concealed bow that fires iron arrows with the pull of a silk thread attached to Hyouko's right wrist. To confuse his opponents so he can hit them with a bullseye, Hyouko shows his left hand, which possess a mysterious glowing symbol that emits a strange sound from it. Also in his arsenal is the Kasuibusuen, a pair of cubes that turn into paralyzing gas when dissolved that stop anyone who breathes just a little bit of it in for four to five minutes, as well as the most obvious of his weapons, the Rokudouko, an object with six blades worn on the Human Weapon's back that can be thrust forward.

After losing to Yahiko, Hyouko had become slightly insane. He had never expected a boy of his age to outsmart and even defeat him at his games. Hyouko was later arrested by the police and what happened to him after remains up in the air.