Being the former Ultimate Blacksmith, Sohnosuke is skilled at developing and using different weapons, and he stocks all kinds of hidden weapons inside his coat. Though usually meant for practical use, he can also make ones for collection purposes and he will forge basically any blade upon request.

Sohnosuke is stated to be a "silent type", who avoids talking to others, the only exception being his romantic partner Ruruka. He is incredibly loyal and very protective of her, drawing a hidden weapon from his coat on any person who gets close to her. Sohnosuke loves Ruruka's candy and Ruruka seems to feed him as a reward, him often resting his head on her lap. Though otherwise calm and serious, the way he eats candy and says "dewicious" is rather comical.

To protect Ruruka, Sohnosuke doesn't hold back and show his full splendor towards his enemy. Without any remorse, he set a trap that severely injured Seiko's right hand and took out all of his hidden weapons to fight her until she reached her demise.

Once Sohnosuke's trust is broken, it is very difficult to gain it back, as he believes "once a traitor, always a traitor". However, he doesn't mind when Ruruka betrays him or even when she takes his life, as he loves her very much and thus doesn't consider it a betrayal.

Even though he is described as "cool" silent character and has a calm voice, in the official English dub he can sound notably angrier and more aggressive, and sometimes he uses language unlikely for the character (for example, "babe").