Now he features Kappa in Sarazanmai.
It’s not rare in Japanese anime.
It’s a mysterious creature (yokai) in Japanese folklore.
They live near water, have plates on their heads called dish (sara) and must keep these wet,
Like to play sumo wrestling,
Love to eat cucumbers.
They are not hostiles against human, but like playing a joke, for example, to drawn men into water.
Specially they pull out shirikodama (尻子玉) from human’s body to gain power.
Shiriko dama literally means hip ball. I guess men have the mythical ball inside the anus to contain power, maybe.
In this anime, the kappa named Keppi (voiced by Junichi Suwabe) collects the shirikodama. I don’t know why, because I have watched only the first episode.
Not only kappa, you may have found these icons.
This shape is kawauso (otter, カワウソ).
Kawauso is an animal, but it was classified as a yokai. And some folklore says old kawauso turns to be kappa.
Kawauso will be an important role in this anime.
One more tip,
When Keppi is called frog by Kazuki and Toi, he gets angry.
Otaku who watched Mawaru Penguindrum know it.
Himari looks for a book titled “Kaeru-kun, Tokyo wo sukuu (Super-Frog Saves Tokyo)”.
The novelist Haruki Murakami (村上 春樹) really published this book.
A man meets a frog and is asked to fight against a big earthworm to stop the earthquake. So the frog (kaeru) saved Tokyo tough no one knows it.
Frog (kaeru) seems to be a symbolic animal for Director Ikuhara.