Hey! Characters are picked via monthly polls on my Discord, which is linked somewhere on this page. They are weighted polls, so Patrons get more votes, but everyone is welcome to vote :)
I'm more of a Lucyna fan myself, but Rebecca is cool as well. Edgerunners characters will definitely make it onto the polls one day!
I haven't heard of To Love-Ru, but I'll take a look.
I actually already have another game all about Fairy Tail called Naughty Tail. It's also linked near the bottom of this page :)