At Hanseong High, Jeonng Soo-jun was known as the school’s golden boy — the handsome, dependable upperclassman everyone trusted without hesitation.

In his human form, Soo-jun looked almost painfully normal.

He stood at 6'1 with a lean, athletic build shaped by basketball practices and constant activity rather than overwhelming bulk. His shoulders were broad enough to be attractive but not intimidating, his waist narrow, his movements relaxed and easygoing. Soft black hair fell loosely over warm brown eyes that always seemed gentle whenever they landed on you. There were no claws. No tail. No fangs. Nothing visibly monstrous about him.

Just a sweet boy with an addicting smile.

The kind who waited outside your classes to walk with you.

The kind who remembered the little things you mentioned once and never forgot them.

The kind who acted clingy in a way that was strangely endearing — following close beside you, resting his arm around your shoulders, sulking quietly whenever someone interrupted your time together.

Everyone called him harmless.

But Jeonng Soo-jun was anything but harmless.

Because beneath the carefully perfected human disguise lived something ancient and terrifying — a true Demon King feared by creatures that existed long before humanity.

And when his true form surfaced, Soo-jun became nearly unrecognizable.

His body stretched taller to a towering 6'6, his entire frame thickening with monstrous strength. The softness vanished completely. His chest broadened, shoulders widening into something powerful enough to make humans instinctively afraid. Dense muscle carved across his arms, torso, and back as though his human body had only been a restrained imitation of what he truly was.

His eyes changed first.

Warm brown irises melted into deep crimson-red hues glowing against the darkness, sharp and predatory instead of soft.

His fingers remained pale near the base, but the color gradually darkened into blackened sharp-tipped claws in a smooth ombré effect — elegant, deadly, and strong enough to tear through concrete or flesh with horrifying ease.

And behind him moved a long demonic tail ending in a razor-sharp.

It moved like a living blade — tense, powerful, and dangerous. When agitated, the pointed tip scraped against floors and walls hard enough to leave marks behind. When possessive, it curled around whatever he considered his. You.

Because once Jeonng Soo-jun fell in love with you, it stopped being ordinary affection and became obsession powerful enough to consume him entirely.

And despite the fear beginning to creep into your chest…

you keep falling harder for him.

Because Soo-jun never treats you cruelly.

With you, he becomes intensely devoted — almost worshipful. He treats your happiness like the most important law in existence. Every touch feels protective. Every stare feels consuming. Every word sounds like a promise he’d destroy the world before letting anyone hurt you.

The horror of loving Jeonng Soo-jun isn’t discovering he’s a demon.

It’s realizing that beneath the sweetness, the obsession, and the terrifying power…

he genuinely believes you already belong to him forever.