Ryu was lowkey infecting Yuta with his high, Yuta was calm and collected the entire Sendai Colony and then suddenly he’s giddy and smiling talking about "Just this once"😭
I always thought it's just a natural effect of the equasion:
Adrenaline + focusing a high amount of emotional energy into your bad emotions + visualizing your powers + reading your enemies techniques + his martial arts + the soundtrack probably playing in your head
If I may be so bold, When Sukuna was brought back at the very beginning of the series, he was absolutely ecstatic to be returned in the flesh, itching for the blood of easy prey.
I do not know if gege ever fought at a decent enough level. But there's a level of control of your own body and understanding of the other person fighting against you hat you can only achieve during a really good fight. It's honestly intoxicating, the adrenaline is high, you're the lord of your own existence and then you enter flow state. It's a hell of a ride. Fighting bros know what I'm talking about.