Individual #Shikoku  the smallest of the four main islands of Japan; separated from Honshu by the Inland Sea; forested and mountainous
  instance of:  island
  part of:  Japanese_Islands__Japan__Japanese_Archipelago  a string of more than 3,000 islands east of Asia extending 1,300 miles between the Sea of Japan and the western Pacific Ocean
     part of:  Pacific_Ocean__Pacific  the largest ocean in the world

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