My Adoptive Sister and Childhood Friend

Anime crossover: Building a multiversal peerage, starting with Grayfia

Author: Loves Watching New Anime

Synopsis:

Lind transmigrated into an anime crossover world, where Grayfia was his adoptive older sister and Rias was his childhood friend.

He even awakened a system that let him recruit his own devil peerage.

From then on...

Devil contracts began spreading throughout the multiverse.

Grayfia: Lind, being your adoptive sister isn't enough for me anymore.

Rias: Lind is the only fiancé I'll ever have.

Shiho Miyano: Master, could you replenish my mana?

Esdeath: Master, please make me stronger.

Erina Nakiri: My God's Tongue is the best.

Before he knew it, Lind had turned the entire multiverse into his own pasture.

Chapter 1: My Adoptive Sister and Childhood Friend

The Underworld.

Inside a training ground at the Lucifugus family's castle.

"Whew!"

After several hours of training, Lind's mana reserves were completely empty.

He gently exhaled, sat on the ground, and wiped away his sweat with a towel, gazing somewhat wistfully at the sky, which was as clear as a pristine lake.

He was a transmigrator, and this was already his second life.

Only a few days ago had he recovered the memories of his previous life.

In this life, he wasn't human, but a human-Demon hybrid.

As an infant, however, he had been adopted by the Lucifugus family on a battlefield, becoming Grayfia's adoptive younger brother.

"Not too bad."

Lind sighed.

He had Grayfia as his powerful backer, along with the Lucifugus family's resources to support his development.

Not long ago, his strength had already reached the level of a High-Class Devil.

For someone his age, that was quite impressive.

But...

"This world is seriously ridiculous."

Lind's eyelid twitched as he recalled the information he had gathered.

This was a world that blended several anime from his previous life.

Just looking at a map of the human world, he could spot one familiar name after another.

Kuoh Town, Fuyuki City, Chiba City... countless anomalies lurked beneath their peaceful everyday lives.

Devils, angels, fallen angels, jujutsu sorcerers, exorcists, and yokai were no secret to a devil like him.

He had even found records of Taimanin and Heretic Gods.

That had nearly made Lind lose his composure.

This world really has quite an appetite. It'll mash anything together.

"I knew I'd find you here."

A gentle voice sounded beside Lind.

Lind turned to look.

A tall woman with silver hair and a cool, aloof bearing came into view.

She wore a pure white dress, and an indescribable air of nobility and wild fierceness radiated from her.

She resembled both a noble young lady and a warrior who swept across battlefields.

The newcomer was none other than Grayfia Lucifugus.

Because of Lind,

her path had long since changed.

Naturally, she had no need to wear a maid outfit.

"Fia, you're here."

Lind smiled, but stumbled as he tried to stand.

The next moment,

something soft pressed against him, and Lind found himself enveloped in warmth.

Grayfia helped Lind to his feet, completely unconcerned that her intimate gesture was giving him a little treat.

"Honestly, you don't need to train so desperately. With me around, no one would dare cause trouble for the Lucifugus family."

Grayfia looked at Lind and gently chided him.

"I just want to get stronger."

Lind shook his head.

This world really made it impossible to feel safe.

Grayfia was strong, that much was true.

But against this world's most powerful fighters, she still wasn't strong enough.

Besides, how could a man hide behind a woman?

"My little Lind will definitely become very, very strong."

A smile appeared on Grayfia's face.

She truly believed that from the bottom of her heart.

Lind's rate of progress was at least as good as that of most pure-blooded Demons, if not better.

Besides...

How could the man I've set my heart on possibly be anything less?

"Fia, could you drop the 'little'?"

Lind was a little exasperated. "I'm an adult now."

"Really? How come I can't tell?"

"Then should I prove it to you?"

As he spoke, Lind slipped an arm around Grayfia's slender waist with a grin.

"Oh? So you're looking to rebel?"

Two rosy blushes bloomed on Grayfia's cheeks, but she didn't avert her gaze.

If not for her desire to preserve a young woman's modesty, she would have confessed her feelings long ago.

"Of course not."

Lind smiled. "I've just used up so much mana that I wanted you to replenish it for me, Fia."

Grayfia froze for a moment.

Lind really seems different.

He's gotten so bold.

Whenever I offered to replenish his mana before, he always turned me down.

But today...

Has he finally caught on?

As she thought that,

She saw Lind's face drawing closer and closer.

"Mmph..."

Grayfia's pupils contracted sharply.

My head... it's burning.

Lind's eyes gleamed as he felt his mana recovering.

Mana replenishment,

was a method of restoring mana through the exchange of bodily fluids.

Among devils, it was a method used only between people who were close.

"Little Lind, tell me the truth. Have you been fooling around behind my back?"

Grayfia's lashes trembled. She lightly pressed her lips together and looked at Lind with a faint pout.

He's far too practiced at this.

"I just have plenty of theoretical knowledge, all right?"

Lind answered without a hint of guilt.

This really was his first time replenishing mana.

As for anything else,

what happened in his previous life obviously had nothing to do with this one.

"Is that so?"

Grayfia blinked, then gave him a challenging smile.

"Then I'll have to make absolutely sure."

"Do whatever you like."

Lind and Grayfia gazed into each other's eyes, as though neither could see anything but the other.

"Ahem."

Just as Lind was about to lose control,

a cough came from the doorway.

Grayfia immediately sprang aside like a startled rabbit.

Her ears burned red, and inwardly, she was frantic.

I'm done for.

This is all Lind's fault.

I didn't even notice someone coming.

They didn't see everything, did they?

"Oh my, it seems I've come at a bad time."

Rias leaned against the wall, a hint of jealousy in her eyes.

Because of the cooperative relationship between the Gremory Family and the Lucifugus family.