Kago. I don't really have a good reason. Just because it's Kago.
With my limited Japanese and her limited English we'd end up learning each others languages in no time. It never hurts to know English in today's world. And having someone to speak Japanese around would be a much easier way to learn for me.
I'd catch her fish and things all the time. I wouldn't allow her to lose a single pound!
I need no other h!p members on the island. Just me and Kago thank you. If anyone else I'd bring Ayaka so communication would be a bit easier. It'd be alot less awkward having her there to correct me on my Japanese grammar and aibon on her English. But then I'd have to fish for three.