Emma couldn't believe what her eyes seeing right now. But it was what it was as Riku showed strong evidence to prove that he wasn't lying at her.
"Riku, I didn't what exactly happen to you. But I think someone put a strong magical curse on you." That was her opinion since the occurrence that transpired to him wasn't an ordinary circumstance.
In his mind, Riku was extremely laughing cause he knew the main reason why he was feeling something like this. Or to be more simple, it was the weakness of his gene which was the dark crow.
The monster and ordinary crow weren't the same. Why? The ordinary crow could freely fly under the yellow bright sun while the Dark Crow monster couldn't survive with it.
Yet, he can't admit that he a curse to Emma, knowing this would find a way to treat him which wasn't good. To didn't get longer the story, he made a faster story and pretended that he recalled something inside his mind.