Art credit goes to Yuu Shishio on Twitter.
Link to their acc: https://twitter.com/yuushishio
Into the middle of the sea, a storm is rocking a pirate ship out of control. One of the crew members was frantically trying to secure the mainmast but the wet floorboards have aggravated everyone's job. That one swordsman member has slipped off the ship and has fallen into the rough waves of the cruel waters. One moment ago, he was struggling to keep the water out of his lungs and the next he sees the most beautiful thing in front of his eye. After he got rescued by his mates, he is lost in his thoughts over the fact that the person that has saved his ass might have been a merman. But one thing he is most certain of. He will for sure meet them again, and when he does, he will do the right thing and thank him.