If you liked the Mysterious Girlfriend X manga, the Anime-Planet community thinks you'd like:
Both manga feature the mysterious girlfriend theme. I can't quite name all the things that make those two similar, but if you can't get enough of that theme, you ought to give them a try.
The main characters are devoted to each other so its a good find itself. Also the main female lead is super mysterious just like in Mysterious Girlfriend X so I am completely sure it won't disappoint.
Both mangas are cute and unusual Seinen romances. Both are a stories about really weird high school student (boy in Love Roma, girl in Mysterious girlfriend X ) suddenly starting a slightly bizarre but really charming romance with a normal student. Whether it's complete honesty and ability to express your feelings in front of a large crowd (Love Roma) or a relationship based on drool, that can convey emotions (Mysterious Girlfriend X) those unusual stories are very heartwarming.
Both mangas are trying to answer some relationship questions (like how to understand the other person, or what dating each other means). The main difference is that Mysterious Girlfriend X is a bit more on the ecchi side, and Love Roma is more on the absurd side.
Both manga are seinen romance comedies about a bizzare high school couple. Simply, if you liked one, you can't go wrong with the other.
Choku! and Mysterious Girlfriend X have one thing in common. You can probably guess what it is yourself: mysterious girlfriends. MGX is really bizarre, on the other hand Choku! tries to be more like a comedy. Anyway, if you liked one of those two manga, odds are you will like the other one as well.
For the last year, Ryouta Kusahana has lived a 'typical' high school life – except for the fact that he refuses to take off a giant dog suit. The only classmate who shows him kindness is class rep Hinako, a girl that Ryouta has fallen in love with. So when the new trainee teacher Ayame catches the boy sniffing Hinako's gym shorts one day after class, Ryouta is devastated and pleads for her to keep it a secret. But Ayame demands a high price: in exchange, Ryouta must let her fulfill her perverse fetish to smell and sniff him, as she's fallen in love with his scent at first sight. Now, though he wants nothing more than to win Hinako's heart, Ryouta must come to terms with this new woman who's wriggling her way into his suit, and all over his body.
Sawako Kuronuma is just like any other high school girl who wants to make friends and be useful. The only problem is she bears a worrying resemblance to Sadako from 'The Ring!' Because of her reputation, people are not only terrified of her, but small dogs even bark in fear at her presence; in fact, the only person in school who will talk to her is the lively class hottie, Kazehaya. As the pair spends more time together, Kazehaya slowly begins to bring Sawako out of her shell and soon their feelings for each other develop further. Though with her crippling insecurities, lack of social skills, and a series of cruel rumors and misunderstandings, it seems that Sawako's dream of a normal life won’t be quite so easy to obtain.
Both series feature a strange, spooky, and unpopular girl who sits alone, until one boy seems something special in her and initiates contact. In both series the pair find themselves in a close relationship, in which they have doubts & uncertainties about their feelings, their partner's feelings, and the overall status of the relationship.