When Ren Kuroda returned home and pushed open the front door, a small figure suddenly launched itself at him like a cannonball.
No—not just the speed of a cannonball. The impact itself was so strong that if it had hit an ordinary person, they probably would've woken up in the ICU.
"Ren! You're back early today! Did you skip school again? I'll tell Mom, you know!…Unless you buy me the newest plush toy. Then your secret is safe with me."
A little girl with wine-red hair tied into bouncy twin tails peeked up at him with a mischievous grin, looking every bit the tiny demon she was.
This adorable sailor-uniform girl currently buried in Ren's arms was his little sister—Tenjouin Ryuhime.
Kujou Hinano, who had followed Ren inside, froze in place. When Ryuhime had appeared, Hinano hadn't seen anything—just a blur. The next instant, the cute little whirlwind was already snuggling into her brother's chest.
Only then did Ryuhime seem to notice someone else standing there. Her cheeks turned bright red, and she hurriedly pulled away from Ren, pretending the whole thing had never happened.
Ryuhime acted like this only at home. In front of classmates or strangers, she was much more reserved.And yet now she felt a sudden, suffocating sense of danger—this was the first time her big brother had ever brought someone home.
A girl, no less.
Her eyes narrowed critically as she sized up the intruder.
Her brother had never brought a woman home before. Not once. And worst of all—she couldn't tell Hinano's exact age, but that cute, childlike face? It overlapped dangerously with her own territory.
Was this girl here to steal her brother away?
Ryuhime felt a storm of anxiety rising.
Well… the girl was pretty, but clearly not as cute as she was. So that was fine.Probably.
After comparing Hinano's pretty face to her own and coming out confidently ahead, Ryuhime lifted her chin triumphantly—until her gaze continued downward.
And she saw them.
Two… pineapples?
Why was this woman so petite yet blessed with such… overwhelmingly large breasts? They were bigger than their mother's!
Before she could stop herself, Ryuhime reached out—her tiny hand acting on instinct and righteousness—and did something Ren had always wanted to do but had never dared.
"I… I lost… Ryuhime has completely lost…"
Feeling the impossible softness beneath her palm, the little girl collapsed to the floor like a balloon with all the air punched out.
Ren gave his sister a look—part envy, part exasperation—before sighing and stepping in.
"Hey, that's really rude, especially to someone visiting for the first time.This is Miss Kujou. She's an auxiliary officer from the neighborhood police division. I'm helping her deal with some bad guys. It's not what you think."
Ren gently bonked Ryuhime on the head, wearing that helpless big-brother expression he knew all too well.
"So… this lady isn't my rival? She's not here to take my brother away?"Ryuhime immediately threw herself back into Ren's arms, clinging to him like a happy kitten.
"That's what I've been telling you. Stop watching those silly soap operas with Mom. We're siblings. Even if Miss Kujou were my girlfriend, she still wouldn't be your rival."
Ren rapped her on the head again—this time harder—completely done with her nonsense.
"As long as there's love, even siblings can—!"
"NOPE." Ren shoved her face away before she could finish, disgust etched into his expression. He turned to Hinano with a forced laugh. "Sorry. My sister's… missing a few screws."
Watching their exchange, Hinano stood quietly to the side, smiling despite herself.
Any suspicion she might've had about Ren earlier had completely evaporated.Someone this gentle and affectionate with his family couldn't possibly be the kind of vicious, twisted murderer they were hunting.
Free at last from his over-affectionate little sister, Ren headed back to his room. His mother was out buying groceries to prepare dinner and hadn't returned yet.
Thank goodness Tenjouin Masami wasn't home right now—if she saw a policewoman standing in the entryway, she would've invented an entire drama out of thin air.
Ren knelt by his bed and pulled out a rectangular wooden box. Inside lay a single blade: a katana around a meter and a half long.
It was probably the only thing his stingy father had ever left him.
A jet-black scabbard. A dark lacquered hilt. A slender, sharp, almost elegant edge—This was no ordinary weapon.
More importantly, it resonated naturally with Ren's demonic energy, almost as if it had been forged specifically for a half-demon like him.
If his adoptive father had left behind something of this level, then that man clearly wasn't just some nameless yokai wandering the world.
And yet, despite Ren treating this sword like a divine treasure, the system had only given it a B-rank.
Weapon: Oni-Kage (Demon Wound)Grade: BDescription: A blade forged by a master demon smith. Upon completion, it released such violent sword-aura that it wounded the craftsman himself. As a result, the sword became his final masterpiece, named "Demon Wound."Effect: Resonates with demonic energy. When imbued, it can unleash a projectile demonic strike—the stronger the demonic energy, the stronger the attack.
As Ren carefully wiped down the blade, Hinano, who had followed him into his room, stiffened in alarm.
Japan held a deep cultural respect for the way of the sword… but modern society did not look kindly on people walking around with lethal weapons. Even kendo dojos mostly kept their swords for display, not use.
"You're bringing that? It's too dangerous. Besides, detectives carry firearms. Even if you had a sword, what could you possibly do if things went south?"
This was the modern age. Guns were king.Could even a master swordsman cut down a speeding bullet with a single strike?
"Miss Kujou," Ren said calmly, "do you believe demons exist?"
"What? Of course not." Hinano blinked in confusion. "Yokai are just old fairy tales adults tell kids. If real yokai existed, they'd probably just be criminals doing horrible things."
She scoffed lightly. If yokai truly existed, humans would've uncovered them ages ago.
"Is that so?" Ren's eyes lowered to the blade in his hands."Then I guess you're about to have your eyes opened tonight.Maybe the reason humans haven't seen yokai… is because they all died before they could tell anyone."