Mendo Suutaro. The mask character with an octopus mouth is a character from the manga "Fukusei Boy", and the mask character with an octopus mouth in Japan is Mendo Suutaro. Japan, referred to as Japan, with its capital Tokyo, is located on the west coast of the Pacific Ocean. It is an arc-shaped island country extending from northeast to southwest, including four large islands of Hokkaido, Honshu, Shikoku, and Kyushu and more than 6,800 other small islands, with a total area of ??378,000 square meters. km.