Demon Slayer: Power and Motivation (Demon Slayer X Devil May Cry)

Prologue

One day, Urokodaki was walking through a village. He was on a simple walk, looking to get some fresh air.

It was then he found an 18-year old girl, standing around. The girl wore a black coat with three separate coattails, along with a pair of dark green pants and brown boots. Her shoulder-length wavy hair was white as the snow, a contrast to her dark blue eyes.. In her left hand was a katana with a black scabbard, blue-and-gold handguard, and a white hilt.

"What are you doing out here so late at night?" Urokodaki asked.

"I don't know." The girl responded, "I just woke up and that...thing tried to attack me, so I killed it."

She pointed her sheathed katana at the corpse of a demon she had just slain. Strangely, the body hadn't disintegrated into ashes yet...

"I see." Urokodaki muttered, "May I ask what your name is?"

"Vivi Kiyo." The girl replied, smiling politely. "Nice to meet you."

"My name is Sakonji Urokodaki." The former Water Hashira greeted, "I'm going to assume you're not from this world?"

"You are correct." Vivi confirmed, "Although I don't remember how I ended up in this world..."

"Well, I would suggest coming with me." Urokodaki proposed, "It's safer than staying out here, and I can answer any questions you may have about this world."

"Alright, lead the way." The girl agreed. While she could easily fend for herself, she would rather be safe than sorry.

Urokodaki nodded and started running, with Vivi following right beside him.

After an hour, they reached Mount Sagiri. Urokodaki looked over at Vivi, and to his surprise the girl hadn't even broken a sweat. She was standing around casually, fixing her collar.

The retired hashira led Vivi into his house. Stepping inside, Vivi noticed that it was silent.

"You live alone?" She asked.

"Not currently," Urokodaki answered, "I have a student under my care. I assume that she's sleeping right now."

The elderly man sat down on the tatami floor, with his visitor sitting opposite to him. Between them was a table with a kettle of green tea.

"So, have you been trained?" Urokodaki asked.

"Yes." Vivi answered, pouring a cup of green tea for Urokodaki as a gesture of politeness. "I'm proficient in Iaijutsu. I can give you a demonstration when we have the opportunity."

He nodded, "Do you know what demons are?"

"I would assume you're talking about the creature I killed before I met you." The girl replied.

He nodded, "Yes, those are exactly what I am referring to."

Vivi then shook her head. "In that case, I don't know what demons are like in your world."

After a rather lengthy explanation from Urokodaki, Vivi finally understood what demons were.

"I think I get it now..." She muttered, "Would you like to know what demons are like in my world?"

Urokodaki nodded. "It would be nice."

"There are two kinds of demons in my world: Pure demons and hybrids. Pure demons are exactly what they sound like, malevolent beings who hunger only for power and nothing else. Hybrids are offspring between a demon and a human. They possess the mystical qualities of a demon, but still retain the physical qualities and spirit of a human."

"Does that mean-" Urokodaki asked, before Vivi cut him off.

"Yes, that means hybrids can choose to fight against demons. I'm one such case."