I received a copy of this manga from the publisher via NetGalley in exchange for an honest review.
One is Enough is a bit of a mixed bag. The artwork of the characters is generally very pretty, but they sometimes look different from page to page (either in appearance or in style), and the backgrounds are very hit or miss, sometimes clearly drawn and other times extremely basic. It can be difficult to tell where/how things are happening due to the really simple backgrounds at time. The very simplistic backgrounds combined with a sometimes-detailed and other times basic artwork of the characters is also just a generally strange combination. Combine all this with a typical storyline for this type of manga, and there isn't a lot of new stuff here for anyone who has read a lot of these stories.
That said, it was enjoyable enough, though I really disliked the romance - neither character was truly likable, and I can't say that I wanted their romance to work out. The one character I really liked had very little page time and I was more interested in his story than the main characters' stories. I was hoping the story would go in a different direction than it was toward the end, but it didn't. If it had, I definitely would have liked this work a lot better. One is Enough isn't terrible, but I didn't think it was great, either - there are just too many other works out there with a similar storyline to this one that simply execute it in a better way.