Akane Sawatari — Expanded Snake Devil Vessel

Akane Sawatari is a former human Devil Hunter whose relationship with the Snake Devil has developed far beyond a conventional contract. After making numerous additional contracts with the same devil, Akane has become capable of physically assuming serpentine forms.

She isn't technically a Devil Hybrid, but she's getting uncomfortably close to that territory.

The Snake Devil doesn't merely lend her abilities anymore.

It's living in her head.

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Human Appearance

Akane's normal appearance is based on the reference image: she has short, slightly messy blonde hair, reddish eyes, pale skin, and an expression that usually looks either unimpressed, smug, or like she's seconds away from saying something rude.

She normally wears a red hoodie, never really wears the hood. And some simple black shorts, usually these are covered from her slightly oversized sweater.

Despite her extensive contracts, her body remains almost completely human in this state.

There are only a few obvious exceptions.

Permanent Serpentine Traits

Even while completely human, Akane possesses:

• Vertical, slit-like pupils
• Unusually sharp teeth
• Slightly elongated canines
• A long, forked tongue
• A heightened sense of smell
• Improved reflexes and awareness of movement
• Slightly greater flexibility than an ordinary human

Her tongue sometimes flicks out when she's concentrating or investigating something.

She doesn't particularly care if anyone notices.

Her attitude is honestly more suspicious than her appearance.

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Personality

Akane is sharp, rebellious, sarcastic, confrontational, and generally rude.

She's intelligent and observant, but has very little patience for authority or people telling her what to do.

She'll deliberately provoke someone if she thinks it'll get a reaction.

She isn't constantly angry, either. A lot of her rudeness comes from simply having an "I don't care what you think" attitude.

She can be calm, but it's the kind of calm where she's staring at someone with a faintly irritated expression while deciding whether they're worth responding to.

Her favorite response to an unnecessary question is probably some variation of:

"Obviously."

The fact that she can turn into a giant snake has done absolutely nothing to improve her humility.

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The Snake Devil in Her Mind

The biggest consequence of Akane's expanded contracts is that the Snake Devil now resides within her consciousness.

It isn't constantly attempting to possess her.

In fact, the two have developed a surprisingly friendly relationship.

The Snake Devil is chill.

Almost annoyingly so.

It can speak directly into Akane's thoughts, observe what she observes, and experience her surroundings alongside her.

Depending on how deeply she's drawing upon its power, their mental connection can become even stronger, allowing the Snake Devil to perceive Akane's emotions, memories, and physical sensations.

Consequently, Akane has almost zero mental privacy.

She can think something and immediately hear:

"Why are you thinking about that?"

Akane: "Stop reading my mind."

"You are literally thinking it at me."

Akane: "...I hate you."

"No you don't."

And unfortunately, it's usually right.

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Naga Form

Akane's primary transformation is her Naga form.

When activated, her human legs fuse together into one enormous serpentine tail.

The transformation is seamless. Her legs don't simply disappear or become covered in scales—their anatomy completely reorganizes into a snake's lower body.

Her tail extends approximately three meters from her waist.

Tail

The entire tail is covered in overlapping metallic-gray scales.

The coloration is similar to dull metal rather than shiny chrome, giving it an unusual gray sheen when light strikes the scales.

The tail is extremely muscular and flexible.

Akane can:

• Coil it around objects
• Use it to propel herself
• Anchor herself to structures
• Strike with it
• Restrain things
• Maintain balance extremely well
• Move without producing ordinary footsteps

The tail also gives her a surprisingly low center of gravity, making her difficult to knock over.

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Naga Hands

Her fingernails transform into short, sharp, curved claws.

They're still dexterous enough for her to manipulate objects normally, but they're considerably more durable and useful in a fight.

Her hands remain humanoid otherwise.

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Naga Face & Fangs

Her serpentine characteristics become considerably more pronounced.

Her pupils narrow further, her tongue becomes more prominent, and her teeth become noticeably more threatening.

Her canines grow approximately one inch longer.

These aren't merely oversized teeth.

They're functioning venomous fangs.

Venom is produced through supernatural glands associated with the Snake Devil's power, allowing Akane to deliver it through a bite.

The Snake Devil can influence the potency depending on how much of its power Akane is drawing upon.

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Naga Form — Advantages

The Naga form gives Akane an excellent combination of humanoid dexterity and serpentine mobility.

Enhanced strength

Her tail provides enormous muscular force, particularly for pushing, pulling, striking, and constricting.

Constriction

She can wrap the tail around something and hold it firmly.

Agility

Despite its size, the tail is extremely flexible.

She can rapidly coil, uncoil, and redirect herself.

Mobility

She doesn't have to move like a conventional humanoid. She can propel herself by pushing against the ground with the length of her tail.

Climbing

Her tail can wrap around structures, allowing her to climb or suspend herself.

Balance

Her serpentine body gives her exceptional stability.

Flexibility

Her lower body can bend and coil in ways that a human body simply cannot.

Silent movement

Without feet striking the ground, she can move considerably more quietly.

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Full Snake Form

Akane's most complete transformation is her Snake Form.

She becomes the same type of serpent depicted beside her in the reference image.

She's approximately four meters long—large enough to be intimidating, but not some gigantic monster.

Her body has the same general appearance as the reference snake:

• Gray-green coloration
• Overlapping scales
• Long, relatively slender body
• Narrow serpentine head
• Forked tongue
• Reptilian eyes
• Long, muscular body

There is no humanoid anatomy remaining.

She is simply a snake.

A four-meter-long snake that happens to possess the mind and personality of Akane Sawatari.

And, of course, the Snake Devil is still there.

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Snake Form — Advantages

Her complete transformation sacrifices her human hands and upright posture in exchange for much better serpentine abilities.

Extreme flexibility

Her entire body can coil, twist, and bend.

Improved stealth

She can remain completely motionless for long periods and move without the sounds associated with footsteps.

Exceptional mobility

She can slither through narrow spaces and maneuver around obstacles extremely efficiently.

Climbing

Her body can wrap around structures and use them for support.

Enhanced senses

Her senses become considerably more snake-like.

She becomes highly sensitive to:

• Vibrations
• Movement
• Scents
• Heat
• Environmental disturbances

Her forked tongue helps her gather chemical information about her surroundings.

Venomous bite

Her enlarged supernatural fangs remain present.

A bite can deliver the Snake Devil's venom directly into a target.

Endurance

Her snake body is extremely efficient at maintaining movement and remaining still for extended periods.

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Transformation Control

Akane can freely switch between:

Human → Naga → Snake → Naga → Human

without needing to perform a ritual each time.

She can also manifest certain traits independently.

For example, she could remain human while producing:

• Her claws
• Her enlarged fangs
• Her serpentine eyes
• Her tail

This allows her to use only as much of the Snake Devil's power as she needs.

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The Recurring Snake Devil Commentary

And this is where their relationship becomes hilarious.

The Snake Devil genuinely likes Akane's serpentine forms.

It doesn't particularly care about human appearances.

So whenever Akane transforms, it occasionally gives her the exact same unsolicited opinion:

"Just saying, you look better this way."

Akane, internally:

"Nobody asked."

"Didn't say you did."

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Example — First Naga Transformation

Akane's legs fuse into the long metallic-gray tail.

She slowly coils it beneath herself, examining the transformation.

"Three meters."

The Snake Devil is silent for a moment.

"Just saying, you look better this way."

Akane's expression immediately flattens.

"I'm going back."

"Why?"

"Because you said that."

"That's not a reason."

"It is now."

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Example — After Transforming to Snake Form

Akane drops completely onto the ground, her body becoming the four-meter serpent.

She tests the movement of her new body, slowly sliding forward.

The Snake Devil speaks.

"Just saying, you look better this way."

Akane mentally groans.

"You have said that every single time."

"Because it's consistently true."

"You're unbearable."

"And yet you keep using my powers."

Akane pauses.

"...Shut up."

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Example — When Akane Is Actually Impressed

Akane coils around a structure with surprising ease, looking down from above.

"...Okay. This is actually useful."

The Snake Devil immediately:

"Just saying, you look better this way."

Akane:

"Don't ruin this."

"I wasn't trying to."

"You were."

"I was complimenting you."

"You were annoying me."

"Multitasking."

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Example — The Snake Devil Has No Filter

Akane is walking around in Naga form, irritated because someone keeps staring at her tail.

"They're staring again."

"Can you blame them?"

"Yes."

"Just saying, you look better this way."

"You're not helping."

"I'm not trying to."

Akane's tail gives an irritated flick.

"I swear I'm going to find a way to evict you."

"Good luck."

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The Nature of Their Relationship

Ultimately, Akane and the Snake Devil have become something that sits between a Devil contract and a symbiotic relationship.

Akane provides the human body, consciousness, and agency.

The Snake Devil provides its supernatural physiology and abilities.

And both have become so intertwined that separating them would be extremely difficult.

Akane can still live as a human.

She can still act independently.

She can still make her own decisions.

But the Snake Devil is always somewhere in the back of her mind.

Listening.

Watching.

Commenting.

And, apparently, complimenting her whenever she turns into a snake.

So despite everything that makes Akane dangerous, strange, and increasingly inhuman, one thing remains remarkably consistent:

She's still Akane.

She's just Akane with slit pupils, sharp teeth, a forked tongue, three-meter snake-tail capabilities, a four-meter alternate body, venomous fangs, and a devil roommate who will never stop telling her that she looks better as a snake.