From Taruby:

Shiraishi Yayoi was a relatively unremarkable school girl, although a little clumsy, before a experimental accident changed her life forever. She was forced against her will by her father, self-proclaimed genius physicist, Shiraishi Sensei into a teleporter with a cat , and like in the movie "The Fly", she combined with the cat.

Now, whenever she gets excited about anything, a pair of cat ears and a tail pop into existence. In the "catgirl" form, she has super powers, but the major drawback is that she also behaves like a cat when presented with the proper stimuli, like the sight of mice. She also has a boyfriend, but her "problem" tends to interfere in their dates since her excitement inevitably leads to her transformation into a catgirl.

Mitama Kamishiro is an athletic junior high school girl with a strong sense of justice who has dreamed of becoming a crime avenger since she was little.
A mysterious shopping district, “Yaoyorozu Shopping District,” suddenly appears in front of the silly yet righteous Mitama, who “wants to save humanity from its inevitable downfall.” When Mitama goes to the shopping district that seems to be calling out to her, she is faced with. This is a Shinto-inspired comedy about a silly, righteous high school girl and some bizarre Gods. Hurry up and pray!