Sonosuke is stated to be a "silent type", who avoids talking to others, the only exception being his girlfriend Ruruka Ando. He is incredibly loyal and very protective of her, drawing a hidden weapon from his coat on any person who gets close to her. Sonosuke is very loyal to Ruruka as he never hold back and show his full splendor towards his enemy in order to protect her. Once Sonosuke's trust is broken, it is very difficult to gain it back, as he believes in "once a traitor, always a traitor”.