Red light is easier on the eyes at night--doesn't cause your pupils to dilate as much.
We put red cellophane on our flashlights when we go out to do astronomy at night--that way we can still read the star map and then not wait for our eyes to adjust as we look through the binoculars or telescope.
This lantern might have been for night time use in a barn for similar reasons.
I found one on ebay in complete listings it sold for 24.00. either way you got a great deal. It might be a repo or restored latern because its in real good condition. One way to know if it a repo look around on it an see if it says made in japan. If it usable then in emergency it priceless.