I'm looking for this yaoi manga I read once but could never find again :c

It features two main characters, one who is light haired and one who is black haired. The light haired one likes the black haired one, and as a joke, the black haired one, who is kind of an ass, agrees to sleep with him. Somehow they end up going on a trip to the beach (or they might've run away), the black haired one falls in love as well, and the two don't want to go home.

The dynamics shift very subtly from the light haired one needing the other to the other way around. I remember one of the reviewers on this site said that that the seme treated the uke very well? Also somewhere in the story was a butt plug vibrator thingy? And at some point the black haired one tells the light haired one that he should "be more selfish, cling to me" (?). The story was kind of short, maybe 5 or 6 chapters. Anywayyys if anyone could help me find it, that would be super duper awesome owo

Koi no Mannaka

Thank you! ^w^