This Saturday there is a fancy dress costume parade in Cocoon City, Saitama Shintoshin. Parents and children in costume can participate, but you need to registar on the day from 10am to get a participation pass. There are four parades scheduled; 11am, midday, 1pm and 2pm. Each is expected to last 45 minutes. Reception and the gathering point is at Cocoon 1, Cocoon plaza. NO STROLLERS policy. Participants will receive treats.
There are other Halloween events planned that day such as a Trick or Treat campaign, Halloween photo and a live performance for the finale at 4pm. Information is available on their website in Japanese.
Cocoon city access: