Lio

Lio lived at the bottom of the ocean for a long time, having been taught to fear the kenomimi up on the land. For years he would spend his life hiding from the kenos that visited the huge mass of water, only daring to go near them once he reached a slightly older age. Inquisitive, he would steal souvenirs from drowned sailors and fisherman and amass a huge collection of keno-belongings in his underwater home. But one day, he felt the urge to investigate the kenos and get closer than he'd ever gotten before. So he took the chance during a freak storm to visit the town on the water, Usami, using his powers to ride the ocean-waves in front of what seemed to be an empty town.

But to his surprise, a researcher from the water science museum nearby named Sen was working late, staying behind his work hours to get some extra time in. The tired researcher was astonished to see the young-looking boy riding the waves, and Lio was just as surprised to see that someone was actually observing his antics. Curiosity took over him and he landed at the docks just as Sen ran up to meet the young boy, the keno asking a million and one questions that Lio didn't know how to answer. But when Sen turned to leave, Lio grabbed onto his lab coat sleeve and walked along with him, intent on following him. 

The two went back to the research center, Sen showing him all the research they had been doing. That was when Lio spoke up and pointed out how some of it was wrong and that it should have been this instead. Amazed that he knew so much information, Sen asked him to visit him if he could, but Lio didn't seem to want to leave at all. So the Tanuki took the younger boy to his car and drove him home, the pair getting to Sen's over-crowded apartment. He was invited inside and the kitten immediately began investigating all the various belongings strewn across the apartment, lifting up and examining each object as though he'd never seen any of it before (most of which he hadn't).

The older male let the other examine all the nooks and crannies of the apartment before settling down to make the both of them a cup of tea. Lio seemed very interested in the hot beverage, licking it out of the cup rather than drinking straight from it. Sen asked him if he had a home to return to and Lio nodded, then choosing to open his mouth and explain how he had an ocean home but he liked this place a whole lot better. So Sen offered to let him stay with him in exchange for Lio's help and intellect of the nearby ocean-life.

Of course, Lio agreed and now goes with Sen to work each day to give his input on things. He's very shy with the other scientists, and will mainly only speak to Sen.