He has blonde hair that he wears in a pompadour and brown eyes. Rantaro is highly self-confident, often referring to himself as Kumicho. He can be quite simple-minded and clueless, and is shown to not be very insightful. Being naturally honest, he displays many of his emotions openly, whether it be happiness, anger, sadness or joy. He wants to be seen as a tough guy, but he is actually a big softie underneath it all. He's a supportive blader beside Aoi Valt.