While it's true that those manga share a common theme (love triangle with two girls who look like very similar), the series themselves are not all that similar. Yet, since both of them are fairly decent and not too well known, fans of one of them might find the other one interesting.
The setting is kind of similar in those two series and so are the characters, though Enchanter ends up being the better one among them. In both series there is this love triangle in which two girls with similar name and appearance (but very different personalities) are involved. What's more in both of those series one of those girls is awfully shameless (older Kiraria in the manga by the same name and Yukanalia in Enchanter). I do encourage you to pick Enchanter if you read Kirara. On the other hand, if you read Enchanter and are considering reading Kirara, keep in mind that there is some nudity there and the quality of the story drops in the middle and never picks up again.
Takaya is the strongest and most handsome guy in school, but also the most misunderstood. His life is irretrievably changed one day when he finds a mysterious pendant and opens it - to his surprise, out pops a beautiful girl with F-cup breasts and wings on her back! Her name is Lilim, she's a succubus, and she also happens to feed off the life energy of humans. Unable to seal her away again, Takaya persuades Lilim not to feed on others, but to stay with him and only take his life energy. However, is Takaya really prepared for the consequences of having a beautiful, live-in succubus interfering with his life?
Both Lilim Kiss and Enchanter feature a male lead who is pestered by this busty demon girl. While not all that evil, the girl stays with the male lead for some practical and rather selfish reason. However, the girl changes (and becomes less selfish) as the series goes on. Both of manga are actually a pretty decent read, so If you liked one of them, you could try the other one too.
This is just a hunch, bot something tells me you could like one of those two manga if you liked the other. Blame it on those rooms you enter through a wall. Surly that's not all there is to it, but I can't think of anything else right now.
What could possibly 3 unrelated series like Unbalance x Unbalance, Enchanter and Gokusen have in common?
In all 3 of those series, the male lead happens to fall in love with a female teacher and in all 3 it takes him a lot of work and maturing to make her feel the same way about him as he feels about her.