Elves can be such stuffy and pretentious folk.
Thus when the boy Yasui was born, he was showered with gifts, and grew up in splendid surroundings. Raised to appreciate both his Human and Elven heritage, Yasui clearly preferred the human side early on. Somewhat manic, Yasui could not fit in well with his Elven relatives, and although too finicky for some humans, they are rowdier. Yasui likes rowdy. It was this preference that led the youth to study swordsmanship, in which he excelled, at least at the level of talent and skill if not in intuition or judgement.