A new hermit crab species of the family Paguridae is described on the basis of two male specimens from Hedo Dome, a submarine cave located on the north coast of Okinawa Island, Ryukyu Islands, southwestern Japan. The assignment of the new species to the genus Eutrichopagurus Komai, 2015 is based on the structure of the gills and right male sexual tube, the article 3 of the antennular peduncle with a prominent tuft of setae on the dorsodistal margin, and the posterior lateral margins of the telson each bearing a prominent tuft of setae. Among two known congeners, Eutrichopagurus crassoculus n. sp. may be closer to the type species of the genus, E. shirakawai Komai, 2015, in having greatly reduced corneas, basally bearing sparse setae, and no small corneous spines or spiniform setae on the dorsal surface of the meri of the ambulatory legs, but is distinguishable by the morphology of the ocular peduncles, ocular acicle, antennular peduncle, and chelipeds.