Nana and Hitomi have been together for several months now. They kissed, they had sex, but their relationship is still a secret for everybody else. However things may be starting to change...
Note: Do not confuse this manga with the oneshot volume. This is an ongoing manga -- a continuation of the oneshot under the same name, continuing the story of Hitomi and Nana. There are four oneshots featuring Hitomi and Nana that take place before this manga, see the Related Series links for more info.
Nana X Hitomi Series List:
Chap: 1-->Even if we're not friends
Chap: 2--> If I kiss her ring finger
Chap: 3--> Chocolate kiss kiss
Chap: 4--> Wishing on the moon...
Chap: 5--> Secret Girlfriends