Christmas decor

Try Kinex Mall. There are also many shops around that area selling christmas trees and decorations.

Dept stores are the best option, go to Tangs or Takashimaya

Tangs, Robinson's, even cold storage has some nice stuff

Most shopping centres actually or try Daiso(:

Japan home? Accessories can try daiso?

Takashimaya, Robinsons, Tangs

Takashimaya, Spotlight, Daiso

You can try Takashimaya.

E-commerce?

Orchard