- Alternative Character Interpretation: Is Urabe a strange girl that Hates Being Touched, or does she actually want to make physical contact with Tsubaki, but wants him to ask first?
- Arc Fatigue: The Idol storyline went on for longer than some people liked (a year in real time) before the arc finally came to an end in chapter 48.
- Audience-Alienating Premise: To those who are bothered by saliva drinking, or to those who simply have trouble swallowing the premise.
- Awesome Music: Especially in the dream sequences.
- Broken Base: The Idol arc. Not only did it take an extremely long time to resolve and required Plot-Induced Stupidity for both the leads, for many it also marked a change in Urabe's personality, causing her to ignore her increasing feelings towards Tsubaki and become increasingly hostile to his attempts to simply make physical contact with her.
- The fact that Urabe and Tsubaki never kiss in the entire series, making it feel like a "Shaggy Dog" Story for many fans.
- Genius Bonus: The covers of the books contain rather large portions of the English language versions of various literary classics — the original Frankenstein for Volume 1, for example.
- Les Yay: Urabe and Oka, exchanging saliva whenever they have lunch (not like that! Granted, it's kinda kinky all on its own...).
- Oka peeking down Urabe's top.
- Not to mention her camera habit — she takes pictures of Urabe any time she gets the chance (including a nude shot from that confrontation with Hayakawa). In the OVA, she takes one group shot before the double date, but then starts snapping artistic solo pics of Urabe, leaving the guys wondering what the hell is going on.
- One True Threesome: Latest chapters a slightly teasing with Tsubaki/Urabe/Suwano. Subverted in chapter 86.
- Squick: Sucking saliva off someone's fingers may not be the most romantic thing for most people.
- Urabe's physical reactions to getting excited are unsettling and gross, depending on the moment. She once suddenly had a bucketful of saliva come out of her mouth when her boyfriend caught her off guard.
- In the anime it's drawn a lot thicker and gooier than it looks in the manga (and in real life), always with a slight yellow tint.
- What an Idiot!:
- Tsubaki, multiple times. Part of it is due to his naïveté, part because he has had the Idiot Ball surgically implanted and partly because his girlfriend is, quite honestly, really weird.
- There's also Ueno, who still has no idea that Tsubaki and Urabe are dating — they may not say it out loud, but their reactions to each other are very unsubtle.
- Urabe gets the Idiot Ball in the base-breaking Idol arc when kidnapped and forced to pretend she's the said idol. She just goes along instead of grabbing scissors and escaping ASAP. Coupled with Tsubaki's inability to realize the idol is pretending to be Urabe, despite her doing a poor job at it, and despite that "Urabe" has smaller breasts than usual, which he's already groped and seen exposed...
YMMV / Mysterious Girlfriend X