I went to Japan, and my host "sister" was
extremely normal.
It was shocking at first, but surprisingly it was the least awkward month of my life.
We went to a dinosaur museum, went to the ocean, temples, went and watched fireflies, played with fireworks, went shopping at the local grocery store, played video games, read manga, watched T.V., talked about social differences and ironies while enjoying frozen mandarin oranges.
Those are my favorite memories.
Just do entertaining things, show him the local sights, and take him to the mall.
Just do whatever feels natural... maybe ask him what he wants to do.