Tokyo: Foam matress - where?

[drummerboy17]

The matress in my gaijin house room is basically a two inch concrete slab with a colourful dropsheet overtop. So....anyone know where I can procure a foam matress? Please help my poor back :b

thanks in advance

[kuro_kitty]

Department stores, second hand furniture stores, furniture stores all stock thicker than average foam futon type matresses.