This is very important, I must ask you have you seen a little yellow rat run around in your house?

Does it resemble this:
Short, chubby, it is covered in yellow fur, and its ears are long and pointed with black tips. It has a small mouth, brown eyes, and two red circles on its cheeks. There are pouches inside its cheeks where it stores electricity. Its forearms are short, with five fingers on each paw, and its feet have three toes. It has two brown stripes on its back, and its tail is in the shape of a lightning bolt with a patch of brown fur at the base. A female will have a V-shaped notch at the end of its tail. It is classified as a quadruped, but it has been known to stand and walk on its hind legs.

If so I belive you have a pikachu living in your house!