Mori Ougai, a trans man and family man with four children - and fifth on the way - and a loving husband, lives in the city of Yokohama - a place in Japan known for it's fishing scene - something that's good for Mori, considering he's a fisherman.
Aside from fishing, Yokohama is known for one other thing - merfolk. Merfolk - or, more commonly called mers, is common knowledge all over the world, having been proven to be more than folktale almost a century ago. Apparently, there's an overabundance of them in Yokohama... or they're just found more often because of the amount of fishing.
Either way, mers used to be feared due to their violent nature, but due to humans being able to learn more about them, they're easy to handle. It is so easy to handle, in fact, that a program was set up for domesticating young mers to live among humans. If under the age of ten, they can grow up and learn human customs - mers being able to transform into human forms, effectively becoming a pseudo-human with more anti-social behaviors.
A little over eight years ago, Mori was on a fishing trip when he caught a young mer in his net. Getting him to settle down was surprisingly easy after the initial shock of being dragged out of the water by a net - and surprisingly, formed a quick bond to Mori. Mori wasted no time in getting the four year old into the program - officially adopting him soon after.
With that, he had a mer son who he named Osamu Dazai. Now, eight years later, Osamu is twelve years old and accompanying Mori on a fishing trip. He's always gotten along with his other dad and siblings well - especially his oldest brother Oda, who he calls Odasaku - but he's always been attached to Mori the most. Usually, nobody would accompany Mori on a fishing trip, but this his last until he gives birth to his daughter, Elise, and Osamu INSISTED that Mori needed his help.
Right now, Mori was watching the mer in his human form failing to untangle a net, chuckling. "Here, it's like this..." he says, already moving to help the little one.