Fate's Slave - Shadow Slave X Honkai Star Rail - Chapter 12: Snow Globe

Xia Yan passed through to the world of Bleach and became an eleven-year-old boy. He was rescued by Renji and Rukia in the Seireitei, and he was studying at Shin’ō Academy, and he was a student of the same class.
He is a top student of the Shin’ō Academy, and he is vying for strength by various teams. In the end, he has entered the first team of secret mobile maneuvers.
He will use punishment to kill every person who tries to threaten the martyrdom and protect his loved one.

- Description from Novelupdates

In the Heart’s Kingdom, a kingdom where vampires reign and humans were nothing but livestock, Lilou, a peasant, found herself being preyed upon by the worst maniacal vampire of his kind. However, as terrifying as what he addressed her as his ‘reserved meal’, this vampire also called her his bride!

Except:

My eyes brood with fear, gazing at the still-beating heart in his hand. “My Lord, pardon me but… is this the bloody proof you promised to show me?” I asked, my voice shook as I gulped down whilst struggling my trembling knees from giving away.

“Mhm… do you now believe I’m good at capturing hearts?” The silver-haired man, bearing those menacing pair of deep crimson eyes stared proudly at me after a nod. I gasped when he clenched his hand and squeezed the fresh heart to smithereen.

“Yes, milord. You’re good at it, literally.” I’m mortified, watching the pieces of the heart fall as he approached. His every step made me take a step back until my back reached a solid pillar.

“Huh,” Samael chuckled briefly, stopping in front of me. His long, pointy nails that were covered with blood traced my elbow down to my hand. Gently, he clipped my forefinger in between his, guiding it before his lips. “Did I pass your test, though?” He asked, the sharp tip of his nail played over the tip of my finger.

I stared at his penetrating gaze as I reluctantly answered, “Barely.”

He smirked, nodding in satisfaction before he pressed his nail on the tip of my forefinger that was quick to produce a drop of blood. “Such sweet aroma.” He whispered, placing my bleeding finger in his mouth and licked it with passion.

His menacing gaze never left mine as he consumed a bit of my blood. “Does that mean you’re accepting my invitation?” Keeping my finger in between his fangs, Samael inquired.

I bit my lower lip unconsciously, my heart within my chest drummed as my back broke into sweats. “But… I’m just…” I paused, hoping my answer would put an end to this. “… I’m just a human.”

Samael clicked his tongue, displeased at my response as he let my finger go. “No,” He whispered.

My entire body stiffened when he bent over, caressing my shoulder up to my neck by the apex of his nose, as his hot breaths prickled my skin.

“You're not just a mere human... you are my human.” He stressed before I sensed his lips part and the tip of his fangs against my skin.

After her parents had both died in an accident, she had to sign an agreement with him to save her family's company.

It was stated in the agreement that he would save her company on the condition that she would allow him to do whatever he wanted with her.

Just because she resembled the woman he had once loved, he had toyed with her a million times and tortured her in every possible way.

He humiliated her in front of others and then abandoned her. She had loved him, but had suffered.

It wasn't until the agreement expires that she finally ran away from him. By the time she left, she was already pregnant.

A few years later, she brought her adorable child back and became strong and cold-blooded. When they met again, he doted on her so much …

“Mr. Xu, are you really a Heavenly Master?”

“As genuine as they come, more real than gold!”

“I’ve heard that your reputation in the supernatural circle is really bad, even to the point where a ghost once called the police saying you were threatening him?”

“Impossible!”

“It wasn’t me!”

“Don’t talk nonsense!”

Xu Yang clenched the Thousand-Year Peachwood Sword in his hand, and said, “What’s the name of that ghost? Would you dare to let him confront me face to face?”

(PS: This book is also known as ‘This Heavenly Master is too Vicious’, ‘Scaring Ghosts Makes You Stronger’.)