(Source:
Megami Tensei Wiki)

Yusuke is a very composed and collected individual, and upon further inspection, this extends to a sense of methodical intelligence and a highly observant nature. He acts with poise and elegance, displayed by his eloquent, poetic way of speaking. He is able to remain calm even in dire circumstances, but can also act dramatically at times; others have pointed him out as weird, and even Yusuke admits that he can be seen as eccentric.