Two girls meet on a train headed for Tokyo. The bubbly girl in white is named Nana and she sits next to a black clad rock girl named Nana as well. They talk briefly and seem to share some common bond, before leaving for their own separate ways. When bubbly Nana looks at an apartment for rent in Tokyo, of course black clad Nana would be there and wants to rent the same apartment. Instead of trying to decide who should get the apartment they decide to share the apartment as roommates. From there their bond grows closer as they help each other deal with their own personal problems.