Japan Atomic Energy Agency has developed several Japanese voxel phantoms and performed simulations using the developed phantoms mainly for radiation protection purposes. In recent years, the techniques have been applied to other research fields including medical fields. This paper summarizes recent research results concerning the Japanese phantoms. The main conclusions of the results are as follows. First, according to comparison of organ doses in the Japanese voxel phantoms to those in Rex and Regina for external photon exposure, it was confirmed that on average, organ doses are slightly larger for Japanese phantoms because of the difference in body size; however, the difference is very small. Second, organ doses were found to be obviously different between standing and lying postures both in external and internal exposures because of the change in body structures; however, in terms of effective doses, the effect is limited. Third, the alpha version of a dose calculation system for remotely supporting X-ray therapy through the Internet was completed.