A small top ten from a fun request!
  1. Me
    I still regret walking out of the first one dad and I wandered in to.
  2. Kids reading thick magazines of this week/month's manga
    It's a very common thing to stand in that aisle of the convenience store and read!
  3. Various collector boxes from popular series at the time
    Pokemon finger puppets with tiny candies, collectable Neon Genesis Evangelion figures...
  4. Anime themed candy
    My dad and I love this soda candy that is still being advertised with Attack on Titan characters on it.
    Soft and tasty and shelved with other bready sweets
  6. Singular bananas
    Basically the easiest fruit to find in Japan and occasionally only fruit
  7. Special brands of vending machine drinks
    My personal favorite being a milk tea called "The Pungency"
  8. Yakisoba buns
    Basically a hot dog bun with Yakisoba noodles in the middle. So tasty and soft!!
  9. so many cup noodles
    There is always an entire aisle dedicated to instant ramen, from UFO giant brand bowls to classic seafood flavored cup noodles.
  10. A very strange soundtrack playing overhead
    Though I like a good deal of Japanese music... The Japanese version of "Let It Go" from Frozen gets played too frequently.
  11. Royal Milk Tea.
    It's what I got hooked on my first time in Japan.
    Suggested by @josh
  12. An excellent array of yogurts and those tiny plastic spoons.
    Suggested by @madeline
  13. Cans of really good draft sake
    2174aeac b8c9 40a8 a824 32628eb875b5
    $13 at the ramen place down the street from @alien and me. $1.65 in the convenience store.
    Suggested by @EricElkins