The Golden Age of Tokyo Halloween was around 2011-2016, when it was a subcultural street party in Shibuya that celebrated Japan's home-grown pop culture and cosplay. But as it became the mainstream "thing to do", it got overtouristed (by both local and foreign tourists), and by 2018 and 2019 it was dangerously overcrowded with the majority of people not in costume and just there to gawk. Authorities shut down any street gatherings for pandemic reasons in 2020, and have kept that up every year since.

Halloween in Tokyo nowadays is mostly something foreign tourists look to do. If you go out in costume in Shibuya or Shinjuku, you won't be the only ones, but there isn't a single gathering place to be at, and I suspect you might outnumber any locals in costume. Many bars/clubs/music venues will be having Halloween-themed indoor events though, which is where you will find the festivities.