[He's being serious because it's about his honest feelings! He goes quiet, pursing his lips into a frown. He's not sure whether to feel relieved that Momo is taking the confession with a grain or salt or be hurt by it.

He thinks about the love potion and wonders if he'd actually be hurt about it if that was still in effect.

He clicks his tongue, feeling a little frustrated. They're not on the same page, per say, for this topic. He draws out a small sigh as he looks elsewhere for a moment before looking back at Momo.]

...Look, that confession that I did? It's real. I do have some feeling towards you. I really did mean to keep it 'cause I didn't wanna cause any stupid mess. But now that it's out, I ain't gonna just treat it like some joke.

[A pause.]

I really do like you, Mikoshiba.