Three new species of chitons are described from hydrothermal vent sites and methane seep sites around Japan: Deshayesiella sirenkoi n. sp. from the hydrothermal vent sites on the seamounts in the northern Mariana Islands area, Placiphorella okutanii n. sp. from Hachijo Depression in the Izu-Ogasawara (Bonin) Islands area where no active vent/seep area has been discovered, but the possibility of hydrothermal activity has been suggested, and Placiphorella isaotakii n. sp. from methane seep sites on the Kuroshima Knoll off Yaeyama Islands. Deshayesiella sirenkoi n. sp. as well as two previously known hydrothermal vent species, Leptochiton tenuidontus Saito and Okutani, 1990 and Thermochiton undocostatus Saito and Okutani, 1990, are vent/seep associated species, whereas the two Placiphorella may be guest species. Additional distributional records are given for the two known species.