Atsumu was never a quiet kind of guy. He was loud and obnoxious. You might say, completely opposite from Osamu... wrong.
Like what Suna keeps telling people, these two still share the same DNA, so yeah, definitely twins.
Atsumu started playing for MSBY Black Jackal and the impression never changed.
Miya Atsumu, 23, setter, faux blonde is a jerk. Noisy and gets carried away easily. He tends to react quickly and later regrets his actions.
Kiyoomi sees the setter not different from anyone's perspective. He hates Atsumu.
Until he realized, that the setter has a soft side, too.
Atsumu is friendly and thoughtful. He loves everyone around him especially his teammates, friends and twin brother. Atsumu even adopted stray animals and placed them in a shelter near the MSBY dorms.
Sakusa was a witnessed to all these. A side very few people know about the blonde. The spiker finds this amusing and he started observing Atsumu more.