It's a very new development and he's not sure how to deal with it, honestly. He's been human almost his whole life--despite the whole 'cursed to not walk in sunlight' think he's been dealing with for years...

At least, back then, he could at least risk the sunlight for an hour and be okay.
But now...

He's got his full attention on ritsuka as she suggests making him one of the things lying around.
Even if her ideas are basic, they're better than the idea he had, to wait until night and ambush them in hopes that they haven't destroyed his things by then. (they'll have destroyed his things by then.)

"--Hey, that's actually not a bad idea? I didn't even consider that...

Not that I can go outside and just build something..."