Kuni appears to be Chibiterasu's first partner. As shown in the trailers, he can help Chibiterasu fight enemies.
Kuni is a small boy who always carries his sword on his back. He wears a one piece, purple outfit, which has a huge tear down the middle. He has a small red, round nose, and small, round eyebrows. He has a bruse on one of his cheeks. His hair is tied into buns on each side of the back of his head which are styled to look like Chibiterasu's winglets (or Paint Brushes).
Based on one image, it appears that he can see Chibiterasu's red markings from the start.
Based on a gameplay video, he appears to have inherited his father's yellow streak (although it doesn't appear to be as strong).