Yeah something tells me the scruffy bagpacker is going to be the sleazebag that at first glance, makes everyone seem uncomfortable with his talks about sex, in actuality, will be the guy that most of the girls want to hook up with. Whether or not the author makes him the villain of the story or gives him a redemption arc is still up in the air.
Meanwhile the scrawny, 20 year old kid with no experience in love will be considered the one who's "destined to ride that alone boat" and none of the women on the island would even consider him as a possible pick for a lover. However over the course of the story he somehow charms everyone with his "kind, gentleman-like nature" and win the heart of at least one of the girls (most likely either the glasses wearing shy girl or the woman who yelled at him for colliding with said glasses girl) maybe be the one who hooks up with all 6 women on the island.
This feels like the manga tie-in to the dating sim game the author wants to make.