The remains were taken out of Japan for reasons such as research.
It will be the fourth time that Ainu remains have been returned to Japan, after a set of remains was returned from Germany in 2017, four from Australia in 2023 and three from Edinburgh University in April this year.
Of the five sets of Ainu remains, three were discovered in the town of Yakumo and one in the town of Mori in Hokkaido. Records show that the remains were dug up in 1865 in both locations.
It is unknown when and where the fifth set of remains was found.
After their return, the remains will be housed at a memorial facility in the National Ainu Museum and Park, or Upopoy, in the Hokkaido town of Shiraoi.
