This is a highly rare collaboration piece featuring popular artist Sayaka Kobori's "Marebo" and Chikatoys' "Chika-san," who is stored inside Marebo's belly. This item was purchased at Sayaka Kobori's solo exhibition and has been carefully stored since then. It has only been taken out of the box once for photography. When you open the belly, a small doll is stored inside, and it can be taken out and put back in. It is stored in a specially made black box, which is also signed on the outside.