So... is Koi Koi 7 finished or not?
NO, it is not finished.
Why?
The anime finished before the manga:
Anime finished: June 25, 2005
Manga finished: January 19, 2007
MangaUpdates contains information about the anime adaptation and indicates that it is incomplete.
Watching Order (by release date)
Here you have all the anime relations we detected ordered by release date, so you can see the reason for this status in context and also use it as watching order.
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Synopsis
Tanaka Tetsuro, eager for a fresh start, enters an all-girls high school thanks to a scholarship.
Unbeknownst to him, he's the only male student, and someone already has a crush on him.
He quickly befriends Asuka, a lively girl, which lands him in hot water with the powerful student council.
Asuka and her five friends, the Koi Koi Seven, are in conflict with the student council, and Tanaka gets caught in the middle of their battles.