The sharing of Drool is what connects Akira Tsubaki and Mikoto Urabe , as well as other girlfriend/boyfriend couples in an very intimate way. The 'bond of drool' refers to the bizarre erotic connection that exists between certain people who have drool bond capabilities. The bond allows two people to share emotions and sensations with each other that are piggybacked onto and through their saliva. It is not known, and author Richii Ushiba's story does not say what was needed, or just what happens, for a drool bond to form, but it is known that it is more common when romantic feelings are involved.
One day at school, soon after Urabe was introduced as the new transfer student, when Tsubaki went to wake up Urabe from an after school nap, he noticed she had a small puddle of 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 symptoms and becomes sick. Thus begins the pair's 'daily routine' of Urabe giving Tsubaki her drool ( and on rare occasions when Tsubaki will give Urabe his drool ) after school as they walk home, making it a major part of their relationship.
Since then, Urabe has been able to, by means of the drool bond, share with Tsubaki her feelings, both mental, emotional and social. She can also implant images into his mind and influence his dreams by somehow putting her feelings and desires into the drool she produces. In Chapter 10 of the manga, Urabe is able to transmit to Tsubaki the image of herself wearing a bikini swimsuit, even though she had on a full length winter coat covering the bikini. Also in Chapter 60 of the manga, Urabe does a similar feat in that she is able to transmit to Tsubaki the feeling of being cold and in a snowfall on the last day of July. 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 that she believes to be sexy (Manga Chapter 0.5, Commentary and Opinion section ), or not wearing any clothes at all, 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, with just a couple of exceptions shown in Chapters 56 & 75, Urabe never sucks on Tsubaki's finger, with all drool exchanges for the pair occurring via transference from her finger. However it happens a few times in the anime, including a scene in a graveyard 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 drool 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 the people who have the drool bond 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 and 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 latter seems to be the case, given the popularity of the movie, as people with real drool bond capabilities, especially males, are quite rare.
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, leaving a very distinct odor, and in Chapter 61 of the manga by a shirt he gave her. In the final chapter, Urabe reveals that kissing would have the same effect as their 'daily routine', since by kissing, 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 of 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.
A full list and a more detailed discussion about the ones who have drool bond capabilities can be found here.
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 Omake (extra) chapter called 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 Tsubaki was 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.