It's yaoi manga kind of similar to Mother's Spirit except in this one the Japanese guy ends up on the brown guys island. I think also there was a goal to make babies
http://www.mangago.me/read-manga/razoku_no_hanayome/ ?
This isn't it but it was an interesting read
It's yaoi manga kind of similar to Mother's Spirit except in this one the Japanese guy ends up on the brown guys island. I think also there was a goal to make babies