@Varicke UV light also gives you melanoma...and worse if she switches to some other types. And how about Microwaves to the nether region? Does that give him power?
Kiiros gains power through anything the sun gives him, you could practically say he's the sun itself in a way that everything from it doesn't harm him. In excess it's better for him. He could stay out in the sun for entire days. As for the nether regions I'm not sure how he'd even react to that lol