(No quirks! This takes place waaay in the past. Time period is up to you, but there's no phones or anything like that.)
Izuku has always loved the sea.
When he was younger, his mother used to take him to the beach. Izuku was always fascinated: water that stretched on for kilometres, that sparkled beautifully in the sun. His icon was All Might: a renowned fishing captain that was as tall as a whale and brought Japan back lots of goodies.
So when he turned 12, he began taking his own little ship out on the water. Sometimes he'd go with Kacchan, sometimes he'd go with older sailors to apprentice under them. This was his dream.
However, when Izuku was 16, he decided to try his first long distance voyage out on the water with Kacchan and some of his friends (Denki, Eijiro, Hanta.) He'd prepared for weeks, kissed his mother goodbye and set out to bring back something great for Musutafu.
Red sky in the morning, sailors take warning. Red sky at night, sailors' delight. He'd unfortunately gotten the former, and now-
"DEKUUU!" Kacchan looked absolutely feral as Izuku fell straight off the boat, into the water as the waves crashed and tugged it in every direction. I'm dead, I'm dead- he thought aimlessly.
That is, until he sees a long scaly tail wrap around him and before he can even process the fact that he's been rescued, he comes face to face with-