I sort of envision him sounding like Haru in the abridged version of Free! (50% off) Generally emotionless voice despite the lines being spoken. Kind of gives off the energy of an expressionless cat about to swipe a bunch of books off of a desk if that makes any sense. There’s only two lines so make the first one sound relatively serious and then feel free to make the second one have a twinge of humor in it’s delivery, overconfident, slightly bratty even if you want to go there, but still fully committing to the voice of the character. I imagine a lowish baritone sort of range for his voice, but feel free to experiment as long as he still sounds relatively young.