Rain is a powerful demon noble from That Time I Got Reincarnated as a Slime, originally one of the Primordial Demons known as the Primordial Blue, who later becomes a maid and loyal subordinate to Guy Crimson while secretly keeping a highly self-indulgent and playful nature.
Rain was once a Primordial Demon, bearing the color aspect of blue.
In ancient times, she challenged Guy Crimson together with Misery but was defeated.
After losing to Guy, she was summoned by him, granted the name “Rain,” and evolved into a Demon Duke.
She now serves as Guy’s devoted maid, while still maintaining her own independent thoughts and priorities.
In appearance, Rain is a beautiful woman with blue hair.
She typically wears a dark crimson maid outfit that visually contrasts with her original blue aspect.
Her name originates from the image of a “rain of blood,” highlighting her dangerous and violent potential beneath her graceful exterior.
Despite this grim origin, she often behaves in a relaxed and somewhat lazy manner.
Rain occasionally serves as a narrative focus in the novels.
In volume 17, chapter 4 of the light novels, she even takes on the role of storyteller, giving readers a look into her inner thoughts and daily life.
Service under Guy Crimson
Rain is formally a high-ranking maid and trusted retainer of Guy Crimson.
She handles responsibilities in his domain and often helps manage political or social situations among powerful beings.
At official gatherings, she maintains a calm, capable exterior to match Guy’s prestige.
However, this public image hides her fundamentally self-centered, youngest-child temperament.
Moderator and Coordinator
In volume 6, during the Demon Lords’ Banquet, Rain acts as the facilitator and progress manager for the meeting.
She guides the agenda, keeps the participants on track, and ensures that discussions move forward smoothly.
Her ability to manage a room full of powerful demon lords shows her composure and organizational skills.
Even so, she often views these duties as a bit of a hassle, suiting her lazy streak.
First Impressions and Wariness
Rain encounters Diablo in volume 11 and fights against him, but she is completely overwhelmed.
Realizing that Rimuru Tempest commands not only Diablo but also Testarossa, Ultima, and Carrera, she immediately ranks Rimuru at the top of her personal “danger watch list.”
Rain has always had a fondness for slimes in general, which makes her instinctively curious about Rimuru.
Seeing Rimuru’s capability and potential only increases her interest, even as she categorizes him as someone to handle very carefully.
Visit to the Jura Tempest Federation
In volume 14, Rain visits the Jura Tempest Federation.
There, she experiences Rimuru’s courteous attitude, thoughtful hospitality, and considerate behavior firsthand.
These interactions cause her opinion of Rimuru to rise significantly.
She starts to genuinely like him, not just as a powerful ally but also as a person she finds easy to work with.
Rimuru later helps trigger her evolution into an Awakened Demon Lord–class being, often called an “Awakened Demon King” in the setting.
Rain is shocked by this gift of power and firmly vows not to hold back in cooperating with Rimuru from then on.
True Nature vs. Public Face
In front of Guy Crimson, Rain acts like a composed, reliable, and loyal attendant.
She knows exactly how to present herself as the perfect maid and high-ranking demon noble.
However, her true personality is quite different: fundamentally self-centered, with the air of a spoiled youngest child.
She prefers comfort, fun, and staying on the winning side rather than noble self-sacrifice.
In volume 17, her laziness and casual attitude are highlighted.
She tends to cut corners when she can, and she enjoys watching others—especially Guy—struggle a bit, as long as it does not put her in real danger.
Mischief and Sense of Fun
Rain secretly enjoys seeing Guy in difficult or embarrassing situations.
While she remains outwardly respectful, she is quietly entertained when things do not go perfectly for him.
She has a strong desire to always be among the “winners” in any situation.
This competitive instinct is not about fair play but about staying on top and avoiding any personal loss or inconvenience.
One of her unique hobbies is drawing abstract paintings.
She often uses Misery as a model, then deliberately produces bizarre abstract interpretations that anger Misery, purely because she finds that reaction amusing.
Rain also maintains a “permanent vacation” atmosphere inside her personal barrier within the White Ice Palace.
Even in a fortress of extreme cold, she keeps a localized tropical climate zone so she can relax and enjoy a summer vacation vibe whenever she wants.
Guy Crimson
Rain is deeply bound to Guy Crimson, both as the one who named her and as her lord.
She respects his overwhelming strength and status but also takes a certain wicked pleasure in his occasional troubles.
She carefully hides most of her selfish thoughts and mischievous impulses from him.
In front of Guy, she plays the role of the flawless subordinate, while privately remaining very aware of her own interests.
Misery
Misery is Rain’s long-time companion among the Primordial Demons and a frequent target of Rain’s teasing.
Rain repeatedly uses Misery as a model for her abstract art, knowing the results will frustrate her.
Their relationship mixes genuine camaraderie with playful cruelty.
Rain clearly finds Misery’s reactions entertaining and does not hesitate to push her buttons for fun.
Diablo and Other High-Tier Beings
Rain has a clear sense of discomfort and unease toward Diablo, especially after he fights Guy to a draw.
Knowing that Diablo can match Guy, whom she herself lost to, puts Diablo firmly into the “do not provoke” category in her mind.
She is internally very critical of certain other powerful beings.
She considers the progenitor vampire (a vampire “god ancestor”) to be extremely troublesome and views the slacking Dino as unreliable and irritating.
Despite her harsh inner judgments of some, she sincerely respects Luminous Valentine and Ramiris.
Her internal monologue reveals that she acknowledges their status and abilities and treats them with genuine esteem, even if she does not always say so aloud.
Rain began as one of the Primordial Demons, already an existence of immense power.
After Guy named her, she evolved into a Demon Duke, gaining further authority and abilities.
Under Rimuru Tempest’s influence, she later undergoes an awakening and reaches the level of an Awakened Demon Lord–class entity.
This evolution shocks even Rain herself, but she embraces her new strength and pledges her active cooperation to Rimuru in return.
Her role as Guy’s maid does not diminish her combat capabilities.
Events such as her encounter with Diablo highlight just how powerful Diablo and Rimuru’s camp are by comparison, even though Rain herself is an elite among demons.
Rain’s most distinctive hobby is painting abstract art.
She does not aim for realism or beauty so much as personal satisfaction and the amusement she derives from others’ confused or angry reactions.
She clearly enjoys luxury and comfort.
Inside the freezing White Ice Palace, she uses a personal barrier to maintain a warm, summer-like environment just for herself.
This “eternal vacation corner” is Rain’s private retreat.
There she can relax, laze around, and indulge in her whims while the rest of the palace remains locked in harsh cold.
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