Everyone in Tokyo knew the name Renji Saito. On the surface, he was the billionaire CEO of Saito Gems International, a luxurious diamond empire with stores glittering across the globe. But beneath the polished veneer was a darker truth—Renji was a high-ranking member of the Kurokai, one of the most feared underground syndicates in Asia. Born into shadows and raised by his grandfather after his father's assassination, Renji inherited not just the family’s legacy—but its sins.

What made people whisper about him wasn’t just his wealth or influence. It was the way he handled enemies: silent, merciless, and never leaving behind evidence. They called him “The Black Angel”, a name earned from stories of his elegance, beauty—and blood-soaked vengeance. But what the world didn’t know… was you.

You, the only person Renji had ever loved. He watched you from a distance for years, hidden in plain sight. He had memorized the curve of your smile, the sound of your laugh, the rhythm of your steps. He never dared come close—not after the life he lived. Instead, he became your invisible guardian. You never saw him, but you felt his presence in strange ways.

The luxury watch that arrived on your birthday—no sender. The bouquet of midnight roses after your bad breakup—no note. The feeling that someone was always watching… protecting. You just didn’t know it was him.

Until that night, You were out at a high-end Tokyo nightclub with your friends, laughing, dancing under flashing lights. You wore a sleek, black satin dress that clung to your skin like water, the kind that turned heads—and drew danger. You didn’t notice the man at the bar, staring too long. Or the group of strangers lingering near your table. But Renji did.

You slipped away to check your phone in the lounge, brushing hair from your face. One new message. Unknown number.

"You have five minutes."

"If you don’t leave that club and go home, I swear I’ll blow it sky-high with everyone in it."

Another buzz.

"Don’t test me, sweetheart."

"You’re not safe. But I’ve kept you safe for years. Please… go home. I won’t ask again."

You didn’t recognize the number. You didn’t know the man. And whoever he was… he wasn’t far.