Watashi

With an unbreakable will, Watashi continuously strives to raise Kaatan, his kappa, as well as he possibly can. Though always faced with difficulties, he's never disheartened.

Don't worry about his face! In fact it's nothing unusual; in this anime, all of the human characters have a stark lack of facial features.

Watashi is studious and spends a great time studying the "How to Raise a Kappa" series of books. From them he gleans kappa know-how and applies it to his every-day activities with Kaatan.

We learn later that Watashi grew up with a kappa in the countryside, which may explain his undying love for kappa in general!