The best place in Sendai for Halloween goodies is Plaza on the 3rd floor of S-Pal beside Sendai Station.
Every year, they have a great variety, and I usually grab some loot from there. This year, I'm on a limited budget so I won't be the Great Pumpkin, giving out treats to the masses. For those with an expense account, Plaza is the place to go. No rocks for Charlie Brown from this joint!
There are plenty of Snoopyish snacks for your Trick or Treaters.
Also Peanuts Goodie bags, stickers, cards tattoos...
That's a heck of a lot of Peanuts paraphernalia!
I didn't want to leave empty-handed so I picked up some Peanuts Pasta. *
*Where's Waldo in the USA.
Also there were some large chocolate coins with a monster attached. I rather like the Devil one.
Other stores in the vicinity had some fairly nice Halloween displays. Curiously enough, the actual Peanuts Store only had a few of the above items, though it did have this nifty t-shirt.
There's a nice bony display at the Science Store including a T-rex with a skeleton in its jaws.
At Jupiter itself, you can buy the *Peanuts Pasta for about 40 yen cheaper if you so desire.
A little hard to find, but if you look around, you can try some Pumpkin beer. Starts off yummy but loses its uniqueness about halfway through.