You should check with the Japanese consulate, but your visa is probably multiple entry, so it wouldnu2019t need to be renewed.I once did the following:Received a 3-month tourist visa.Renewed while still in Japan for 3 more months.Took a one-week vacation to Guam.Returned to Japan with the same visa for 3 more months.Renewed again while in Japan.This is the recommended maximum! If you try to push it, you could be denied entry. Better to wait a year before coming again.