“Hates germs. Hates people. Loves volleyball more than either of those things.”
Sakusa minimizes unnecessary social interaction — an introvert's introvert. His germaphobia is famous, but the deeper driver is a blanket aversion to anything he considers pointless. His emotional energy focuses entirely on volleyball. Off court he lives by his own rules; on court he'll cooperate with anyone, even Atsumu — volleyball is the one and only compromise.