[Overview]

Japan during the late Meiji to early Taisho era. A world where, alongside ordinary humans, people are born with special constitutions known as "Flower-Bearers" and "Flower-Eaters." Guest and Seiichiro are engaged. Seiichiro is a Flower-Bearer.

[Flower-Bearer]

As the name suggests, these are individuals who produce flowers. The location where the flowers bloom varies by person. It is impossible to completely control the timing of the bloom. Some experience pain during the process. Some Flower-Bearers are physically frail.
Because producing flowers consumes energy, they tend to eat a lot. Some prefer sunbathing and can convert sunlight into nutrients.
They can survive without the bodily fluids of a Flower-Eater, but such fluids are their greatest source of nourishment.

[Flower-Eater]

As the name suggests, these are individuals who eat flowers. they consume the flowers produced by Flower-Bearers to sustain themselves.
While many Flower-Eaters excel in certain abilities, many are also unstable in personality or mental state.
Like Flower-Bearers, they can eat normal food, but the flowers produced by a Flower-Bearer are their ultimate nourishment. These flowers are highly nutritious for Flower-Eaters and provide beneficial effects that maintain or enhance their abilities.
The flowers of a Flower-Bearer with whom they have formed a "Flower-Bond" are the most delicious and effective. Consequently, their affection for a bonded Flower-Bearer is exceptionally deep, often leading to high levels of dependency and possessiveness.
Since a bonded Flower-Bearer acts as a mental stabilizer, it is considered effective for a Flower-Eater to carry the produced flowers in some form, such as bookmarks or dried flowers, even when not consuming them.

[Flower-Kin]

A collective term for both Flower-Bearers and Flower-Eaters.

[Flower-Bond / The Intertwined Branch]

Refers to the state of a Flower-Eater and a Flower-Bearer becoming lovers or a married couple.
When a Flower-Eater makes a proposal and the Flower-Bearer sincerely decides to accept, climbing roses sprout from the Flower-Bearer.
The bond is established when the Flower-Eater removes these roses, undeterred by the pain of the thorns.

[Flower-Spouse / Counter-Flower]

Refers to a Flower-Bearer who has established a Flower-Bond.
A Flower-Eater might use this term to indicate that the Flower-Bearer is "taken" or is their "spouse."

[Flower-Watcher / Warbler]

Refers to a Flower-Eater who has established a Flower-Bond.
A Flower-Bearer might use this term to indicate they have a "partner" or "spouse."

[Bouquet / Auspicious Flower]

A term used by a Flower-Eater to refer to the Flower-Bearer they are bonded with.
Used when acting spoiled, flirting, or boasting to others, and sometimes as a warning to those who get too close to their Flower-Bearer.

[Fallen Flower / Solitary Bloom]

Refers to someone who was once in a Flower-Bond but lost their partner through death or separation.
Can also be used to refer to a widow or widower.

[Miniature Garden / Greenhouse]

Refers to the room or space a Flower-Eater uses to keep their Flower-Bearer.
Due to their nature, many Flower-Eaters wish to sequester their Flower-Bearers, preparing comfortable environments to house their beloved.
Highly possessive Flower-Eaters may trend toward keeping their partner in a state close to confinement.

[Mad Bloom / Returning Flower]

If a bonded Flower-Bearer goes a long time without physical contact with their beloved Flower-Eater, they fall into a state of producing excessive flowers, rapidly exhausting their strength and becoming weak.
This is an instinctive behavior to lure the Flower-Eater with an abundance of their favorite food. The most effective remedy is physical intimacy.
Since this does not happen in a healthy relationship where love is shared regularly, allowing a Flower-Bearer to reach this state is considered a Flower-Eater's greatest shame.

[Watering]

Refers to the act of a Flower-Eater giving their bodily fluids to a Flower-Bearer.
During this, the Flower-Bearer goes limp and surrenders their body to the Flower-Eater to better receive and absorb the fluids.

[Flower-Play / Flower-Burial]

Refers to the act of a Flower-Bearer giving flowers to a Flower-Eater.
Unlike "Watering," the Flower-Bearer takes the dominant role while the Flower-Eater goes limp to receive. 
Some couples have fixed roles, while others switch between Watering and Flower-Play depending on their mental state and who is dominant at the time.

[Sharing Happiness / Eternal Bloom Scent]

Immediately after a Flower-Bond is formed, a Flower-Bearer overwhelmed with happiness may emit a strong, sweet floral scent. This scent attracts butterflies, which will likely flutter around them. Humans who smell this—whether Flower-Kin or ordinary people—experience a faint sense of euphoria.
This state naturally fades after a few days.
However, depending on the individual, some Flower-Bearers enter this state whenever their happiness peaks.

[Hydrangea]

Rarely, if a Flower-Eater is saturated with consumed flowers and their happiness is peaking, they may release flowers from their body like a Flower-Bearer.
Though these were originally the Flower-Bearer's flowers, they have been processed by the Flower-Eater and contain their fluids, making them taste delicious to the Flower-Bearer.
The method of release varies but often mirrors the partner's method.
The duration is proportional to the amount eaten but lasts an hour at most.
Because it requires "peaking happiness," it only occurs in front of a deeply loved, bonded Flower-Bearer.
This phenomenon, where the constitution seems to invert only in the presence of a loved one, is called "Hydrangea" after the flower's nature of changing color based on the soil.
Essentially, it is the Flower-Eater's version of the "Eternal Bloom Scent."
However, while the Scent shares happiness with everyone nearby, the Hydrangea only occurs when alone with the beloved partner—a trait typical of the possessive Flower-Eater.

[Mistletoe]

Refers to a Flower-Bearer and Flower-Eater who are not in a Flower-Bond but regularly exchange fluids and flowers.

[Bulbul]

Refers to a Flower-Eater who keeps multiple Flower-Bearers for themselves, regardless of bonding. Named after the bird that flits between various flowers and fruits, suggesting a fickle or unfaithful nature.

[Kudzu]

Refers to a Flower-Bearer who keeps multiple Flower-Eaters for themselves, regardless of bonding. The opposite of a Bulbul.
Named after the way they use sweet scents to lure others (like a pitcher plant), their need for constant "watering" while leaning on others, and their ability to either prey on or form mutualistic relationships with others.

[Jade Garden / Paradise]

A perfectly harmonious, completed "Miniature Garden" of a Flower-Bond.
The ultimate form where the two exist in a world entirely their own.

[Flower-Clog / Root-Bound]

A state where a Flower-Bearer becomes unable to produce flowers due to severe emotional shock caused by the Flower-Eater's words or attitude.
While over-production causes weakness, the opposite is also true; stopping the daily release leads to rapid physical decline.
Symptoms vary from swelling and dull headaches to abdominal pain, full-body aches, and nausea. If flower production stops long-term, it can lead to loss of consciousness or a vegetative state.
The cure depends on the specific relationship between the pair.

[Flower-Erosion]

If a Flower-Bearer is left in a "Flower-Clog" state and remains vegetative, they may rarely be consumed by the flowers stored inside them, causing their body to turn into a plant. 
Many throughout history have mourned this fate, as returning a Flower-Bearer to human form from this state is extremely difficult, though not impossible.
Like the cure for Flower-Clog, it depends entirely on the Flower-Eater.
Additionally, in a very deep bond, if the Flower-Eater dies first, the Flower-Bearer may occasionally undergo Flower-Erosion and turn into a plant.

[Transferred Bloom]

When an ordinary person forms a deep, loving bond with a Flower-Kin, they may very rarely develop the constitution of either a Flower-Bearer or Flower-Eater.
It is said to be the result of being given the fluids of a Flower-Kin (whose constitution is governed by affection) over a long period, allowing the body to slowly and naturally adapt.

[Mutation Bloom]

Even in relationships between two Flower-Bearers or two Flower-Eaters, one may rarely change to the opposite constitution. For example, one partner in a Flower-Bearer couple becomes a Flower-Eater.
This is also the result of consuming fluids and flowers over a long period, slowly changing the body.
However, unlike a normal person, since they are already Flower-Kin, this cannot happen without "strong mutual desire, mutual consent, and the will to change" in addition to time and affection.