Drool is what connects Akira Tsubaki and Mikoto Urabe. The 'bond of drool' refers to the bizarre connection that exists between certain people. The bond allows two people to share emotions and sensations with each other through their saliva. It is not known what was needed for a bond to form but it is known that they are more common when romantic feelings are involved.
One day, when Tsubaki went to wake up Urabe from an after school nap, he noticed her drool on her desk. After she left, he tasted it and since then, if he doesn't get a regular dose of it, he goes through withdrawal and becomes sick. This begins the pair's 'daily routine' of Urabe giving Tsubaki her drool after school as they walk home, a major part of their relationship.
Since then, Urabe has been able to share with Tsubaki her feelings, both emotional and physical. She can also implant images into his mind and influence his dreams by somehow putting her feelings and desires into the drool she produces. She occasionally makes him very aroused (indicated with a nose bleed, a rapid heartbeat, and sometimes feelings of being hot) by dressing in particular ways ( or not wearing any clothes ) that she believes to be sexy, thereby producing an 'enhanced' drool.
Urabe can also ascertain Tsubaki's feelings, and sometimes what he's thinking of, by tasting his drool. Because of this, the pair find it difficult to keep secrets from each other regarding their relationship.
In the manga, Urabe never sucks on Tsubaki's finger, with all drool exchanges for the pair occurring via her finger. However it happens a few times in the anime, including a scene where they taste each other's drool at the same time.
While the bond primarily exists between Urabe and Tsubaki, Urabe also, somewhat reluctantly, shares a drool bond with Ayuko Oka. This allows them to share emotional 'notes' on how their respective relationships with their boyfriends are progressing. Others seem to be able to form the bond ( each person that has these capabilities is reveled, one-by-one, as the story progresses ), the only common catalyst seeming to be the drool routine is similar with Urabe or Tsubaki's drool bond, and they have an awareness of what it can do.
Somehow, Matsuzawa of the Film Studies Club manages to come up with the idea of a drool bond between a boy a mysterious girlfriend for the club's film for the cultural festival. This causes a small meme of couples uploading photos of them performing the 'daily routine', but it is unknown whether they actually experience the full extents of the drool bond, or they are just mimicking the routine.
The bond has also been shown to work via sweat for Tsubaki and Urabe. As well as licking her arm, Tsubaki was also able to unknowingly imprint some feelings into her bed as he took a nap in it, and a shirt he gave her. In the final chapter, Urabe reveals that kissing would have the same effect as their 'daily routine' as they would still be swapping saliva.
It is never explained how and why such drool bonds exist, or why Urabe seems to know quite a lot about how it works when she's never had a boyfriend before.
- Form a bond between lovers.
- Transfer emotions---
- Happy emotions and love are said to taste sweet.
- When Tsubaki and Urabe fail to kiss one time, Oka mentions Urabe's drool tastes 'bittersweet' as a result. However, she clarifies it's not all that bad a taste.
- Tsubaki will sometimes feel heavy and slow if Urabe is upset.
- All characters sharing a bond have been shown to uncontrollably cry or smile depending on the situation.
- Transfer physical feelings (including sharing cuts, grazes, and other physical ailments).
- Sexual or emotional arousal, including nose bleeds and hot flushes when exposed to 'enhanced' drool.
- Help cure colds.
- Induce dreams.
- Transfer memories and images.
Overflow of drool
When Urabe becomes extremely happy, or has erotic thoughts, a large volume of her drool bursts out of her mouth. In the extra chapter Special Moves Report, this is called 'Drool spout', and resembles vomiting.
Other characters (usually girls) are also shown drooling in the series, which usually ends up being important to the plot:
- While the core premise of the series is that Tsubaki will go into withdrawal without the 'daily routine', withdrawal never happens again, and he manages to survive a week without it while on vacation during the summer.
- While Urabe's sweat does allow for the transmission of feelings, images and other emotions, it's unclear whether or not this means other bodily fluids can. When licking some of Tsubaki's blood, Urabe does not indicate whether she can or cannot feel his emotions through it. However, she was trying to teach him a lesson and may not have been forthcoming on what she had experienced from him..
- Similarly, it is unknown if tears would work for the bond, but it's worked into the Mysterious Girlfriend Y movie to explain Tsubaki's accidental departure from the script during the climactic scene
- While Urabe's drool overflow occurs more than once in the anime, it only happens the one time in the manga and never mentioned again. However, while pushing quite hard to see Urabe's face under her mask when she has a cold, she mentions his insistence has caused her to produce more drool than usual.