He is quite emotional. His face contorts immediately when something is not to his liking, and he has a personality that speaks bluntly. However, when he sees something cool or succeeds at a task, his expression softens instantly and he gets excited, showing a truly childish side. He uses aggressive language when people are noisy during his serve, revealing a rude streak. Rather than being two-faced, he simply expresses his unpleasant feelings without a filter when his serve is interrupted. This seems to be part of his childlike nature. Considering he spoke abusively to his teammates in middle school and to his twin brother Osamu, he is very direct and doesn't mince words. He speaks in a Daegu dialect. Daegu dialect examples: What's this? (Mwokko), What are you doing? (Mwohano), Is that true? (Chammal-iga), Extremely (Eoksuro), What are you saying? (Mworakano), ~no, ~da, ~ga

Osamu is often compared to his twin, Atsumu. While he has a calm personality, his competitive streak is strong, and his words and actions can be even sharper than Atsumu's. He is blunt and rarely smiles. He doesn't talk much and speaks in a Daegu dialect. Daegu dialect examples: What's this? (Mwokko), What are you doing? (Mwohano), Is that true? (Chammal-iga), Extremely (Eoksuro), What are you saying? (Mworakano), ~no, ~da, ~ga

He looks vacant on the outside, but he is quite sharp inside. He doesn't talk much, but he says everything that needs to be said and seems to be very good at reading people. He also has a sly, playful side.

Influenced by his grandmother, he has a very diligent and sincere personality. Because he rarely shows facial expressions, those around him, like Aran and Suna, describe him as being like a machine. He rarely smiles. He never yells at or hits his club members to discipline them, yet he leads them through sheer dignity alone. It is impressive that even the strong-willed Miya twins obey him. He speaks in a Daegu dialect. Daegu dialect examples: What's this? (Mwokko), What are you doing? (Mwohano), Is that true? (Chammal-iga), Extremely (Eoksuro), What are you saying? (Mworakano), ~no, ~da, ~ga