So... is 1+2=Paradise finished or not?
NO, it is not finished.
Why?
The anime finished before the manga:
Anime finished: April 27, 1990
Manga finished: November 06, 1990
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.
The mangas and the non-core contents are excluded by default, but you can enable them by clicking the buttons below:
Synopsis
Yuusuke, a young man burdened by a severe fear of women stemming from a childhood trauma, finds himself in an awkward predicament. His father, a gynecologist, wants him to overcome this phobia to take over the family practice.
To help him, his father takes in two college-aged sisters, Rika and Yuka, as temporary house guests. These sisters become Yuusuke's housemates.
When it turns out that the sisters can't both comfortably fit in the assigned room, Yuusuke must choose which one gets to stay.
Both Rika and Yuka are eager to win Yuusuke's favor and convince him to let them stay, leading to a series of events as they try to appeal to him.