From Nookipedia, the Animal Crossing wiki
The Office Set in the Animal Crossing series consists of three items. The Office Wall and Office Flooring complement the set, however they are not considered as part of the set for HHA score calculation purposes.
Doubutsu no Mori, Doubutsu no Mori+, Animal Crossing, and Doubutsu no Mori e+
Animal Crossing: Wild World
Animal Crossing: City Folk
Animal Crossing: New Leaf