Since a similar copper disk (or cymbal) yokai was depicted in "Hyakki Yagyo Emaki" (The 'Night Parade of One Hundred Demons' Picture Scroll) in the Muromachi period, some believe that Nyubachibo was modeled on it.
室町時代の『百鬼夜行絵巻』にも同じような銅盤状の妖怪が描かれているので、これがモデルになったという説がある。