A new pedunculate barnacle, Ashinkailepas seepiophila gen. and sp. nov. has been recovered from a hydrothermal cold seep at 1175 metres of depth off Hatsushima Island, Sagami Bay, central Japan. It is the second record of a Neolepadinae, otherwise known from vents, from a seep, but the two are not closely related. Its coarsely ornamented capitular plates, and primary peduncular armament being in whorls of six plates, distinguish it from all previously known neolepadines, not only as a new genus and species, but also as a distinct clade, and therefore a new tribe is proposed to accommodate it. There is a slight bilateral asymmetry in the proportions of the capitular plates as well as a marked bilateral asymmetry in the arrangement of the peduncular scales related to bending over to one side. This apomorphic characteristic distinguishes the new species from all other Scalpellomorpha. While leaning over to one side is suggestive of verrucomorphs, it is not judged a sign of affinity. Ashinkailepas is apparently the most primitive of the vent/seep barnacles, which are considered relics largely of the Mesozoic age.