It's a topic that Yusuke prefers not to linger on. His friends know that he barely eats but that's something different than Hifumi. They've barely interacted and she's a classmate, someone who doesn't have to be bothered by his troubles.

"I can't recall anything but that...Oh! I saw a beautiful looking little mosquito. It buzzed just as they do where we come from and so it still wasn't the most aesthetically pleasing. But then it bit me and I think the mystery is solved." Nobody ever said Yusuke was a genius but he's not an idiot by any means.