What the hell? Grandfather claims he loves his granddaughter, but can't even be arsed to explain anything to her? Tachibana Roku, you sad excuse for an author, you don't deserve being published.
Yeah, the grandfather's an asshole for just dropping her like a hot potato. He clearly doesn't give a shit about her.
If you don't decide on a bet before the competition, you can't just pick whatever you want. You lost your right to win something the moment you didn't ask for something before competing.