Why Fushimi Gaku Became the Demon Lord: The Last Boss's Justice
A major incident shakes the virtual streaming world. Fushimi Gaku, a popular VTuber from the second generation of Nijisanji, suddenly stops all broadcasts. The only official word is an indefinite hiatus. No reason is given, and his presence slowly fades from fans' memories. But in a place no one knows, Gaku is caught up in a different battle.
It begins with a single message from a girl named Miyako. She confesses that her older brother has gotten involved in illegal modification streams behind
Why Fushimi Gaku Became the Demon Lord: The Last Boss's Justice - The girl who acts like an older sister — In a back alley of Akihabara, he is told that his brother became a man-eating monster.
The afternoon in Akihabara always smells the same. The oil from fried food, the scent of plastic casings radiating heat, the sweat of crowds—all of it mingled into that distinctive atmosphere. The main street of the electronics district was packed with tourists and shoppers. Conversations in foreign languages, the shutter sounds of smartphones, anime songs spilling from some shop or another. All of it became one noisy mass, drifting through the humid July air.
Fushimi Gaku, with that clamor at his back, deliberately stepped into a back alley with fewer people.
Just one street over from the main road, and the world became astonishingly quiet. Old mixed-use buildings lined both sides, dim even in broad daylight. Faded posters peeled from the walls, and on the asphalt underfoot, an empty can—no telling who'd dropped it—lay rolling.
(Café Noir, huh.)
Gaku checked the map app on his phone as he searched for a landmark. The meeting spot Miyako had designated was a small café further down this back alley.
Three days had passed since that consultation email.
Between university lectures, during his night streams, the words of that email had clung to a corner of Gaku's mind. Ayatsuji Minato's transformed stream footage. The emotion amplification filter, the personality overwrite module, Nocturne. Every one of those words existed outside the world Gaku knew.
And now, today.
Gaku was going to meet Miyako. A seventeen-year-old girl who wanted her brother saved.
(It's fine. I'll figure something out.)
Even as he told himself that, his steps grew naturally heavier. This wasn't just fan support. He might be about to touch the darkness of a massive agency called Nijisanji. His own sense of justice was leading him somewhere irreversible. The premonition he'd felt that night in the university's back courtyard pulsed quietly in his chest once more.
Café Noir stood quietly on the first floor of an old mixed-use building.
A black wooden door with a small handwritten sign. Orange light spilled from the windows, and in the mid-afternoon back alley, it alone seemed severed from time. Gaku pushed the door open. A bell chimed.
The interior was small. About five counter seats and three two-person tables. Old record jackets decorated the walls, and jazz played softly from a speaker. Not a single customer. Behind the counter, a white-haired proprietor silently polished a glass.
And at the very back seat—
A black-haired girl sat with her back straight.
A white blouse and a navy pleated skirt. A high school uniform, perhaps. Her bangs were cut in a straight line, pinned on the left side with a small clip. Her narrow black eyes stared directly at Gaku. In those eyes, nervousness, wariness, and a faint sliver of hope mixed in complex layers.
(Miyako.)
Gaku knew instinctively. No mistake. This was the girl who'd sent that email.
As Gaku approached, Miyako stood up in a fluster. The chair clattered softly.
Um, are you Fushimi Gaku-san?
Her voice was small, faintly trembling. She pronounced each word carefully, slowly, as if choosing them. The physical distance between her and Gaku was still about two meters. Her body wasn't fully facing him—she held herself half-turned, slightly drawn back. A stance ready to flee at any moment.
Yeah, that's me. Fushimi Gaku. Thanks for coming all this way.
Gaku answered in the softest voice he could manage. With someone on guard, you had to put them at ease first. He never thought the skills he'd honed streaming—closing the distance with first-time viewers—would come in handy here.
No, I should be the one thanking you for coming... truly, thank you so much.
Miyako bowed deeply. Her black hair swayed smoothly, falling over her slender shoulders. Gaku sat in the seat across from her and gestured for her to sit too. After a moment's hesitation, Miyako slowly lowered herself into the chair. Even then, her body still wasn't fully turned toward him.
Want something to drink? I'm pretty thirsty. I think I'll start with an iced coffee.
Oh, then I'll have... the same.
Gaku ordered two iced coffees from the proprietor. The man nodded silently and began preparing them with practiced hands. The sound of dark liquid pouring into glasses filled with ice echoed through the quiet café.
So, um... Miyako-chan, is that okay?
Yes. I'm Miyako. My real name, well... I can't tell you. I'm sorry.
No, no, that's totally fine. I don't stream under my real name either. You can just call me Gaku.
Then, Gaku-san it is.
Miyako gave a small nod. The gesture was somehow puppy-like, and Gaku nearly felt his lips loosen into a smile.
The iced coffees arrived. Gaku took a sip, and Miyako timidly put her lips to the straw as well. Perhaps the sensation of cold liquid passing down her throat loosened her tension a little—the strength drained from her shoulders.
That was when it happened.
Gaku-san, are you eating breakfast properly?
The sudden question made Gaku blink.
Huh? Breakfast?
You have the face of someone who hasn't slept. There are faint dark circles under your eyes. Your skin's a little rough too. If you don't sleep properly and eat properly, you'll collapse before you can even save my brother.
Miyako stared at Gaku's face with a serious expression. That gaze was different from the wariness of before—something else entirely. Concern, perhaps. Being lectured on health management by a younger girl. Gaku was taken aback and couldn't help but smile wryly.
Uh, well, I'm twenty, you know...
That doesn't matter. It's not about age—it's about lifestyle habits. I know it's odd for me to say this, but university students living alone generally have terrible eating habits. Gaku-san, what did you eat last night?
Uh, last night... convenience store onigiri and cup ramen...
See, I knew it. That's no good. You need to eat vegetables too.
Miyako sighed as if exasperated. Then she took something out of her bag. A small bundle.
Here, if you'd like. I made these this morning. I still have extra onigiri.
Gaku stared blankly at the bundle held out to him.
(What is with this girl.)
Handing homemade onigiri to someone she'd just met. And she was the one asking for help. As Gaku accepted the bundle, he felt something warm spread slowly through his chest.
Thanks. ...But are you sure? Isn't this your own portion?
I can't eat much in the mornings. Besides, I figured you must be hungry, Gaku-san.
No, I mean, I appreciate the sentiment, but I'm the older one here. I'm supposed to be the one protecting, not being protected...
The people who protect others are exactly the ones who need to eat properly and sleep properly. I'm saying this as your big sister, so there's no mistake.
Miyako relaxed her lips just a little.
It was the first smile she'd shown—one befitting a girl her age. Her narrow eyes curved like a cat's. Gaku lost his words for a moment at that smile.
(Ah, this girl really is...)
She really was worried about her brother. Without even understanding how precarious her own situation was, she could still concern herself with someone else's health. That earnestness squeezed at Gaku's chest.
The face of his brother back home surfaced in his mind.
Between farm work, his brother had always sent vegetables, worrying about his younger sibling going to university in Tokyo. "You go do what you love," he'd said, pushing him forward. That brother, too, was someone who put his younger sibling before himself—just like Miyako.
(I have to protect this girl, no matter what.)
Deep in his heart, Gaku thought this with conviction.
This was no longer just an investigation.
...I'll have the onigiri.
Gaku opened the bundle. Two slightly lopsided triangular onigiri wrapped in nori. The fillings were pickled plum and salmon. He bit into one—the salt was just right, and the rice was plump and tender.
Delicious.
I'm glad. Is the flavor too light?
No, it's perfect. Really delicious.
When Gaku said that, Miyako let out a breath of relief. That reaction was so earnest too, and Gaku felt his chest tighten.
For a while, they continued with light conversation. About university, about streaming, about favorite foods. Miyako still spoke politely, but occasionally she showed expressions befitting her age. Her wariness hadn't completely dissolved. But the distance between them had definitely shrunk compared to before.
So, Miyako-chan. About the main topic.
When Gaku brought it up, Miyako's expression tightened.
Yes. ...It's about my brother. Ayatsuji Minato.
Miyako took a tablet from her bag. She operated the screen and placed it in front of Gaku.
Everything I'm about to show you, I gathered all by myself. I've never shown it to anyone. ...I thought you were the only one who'd believe me, Gaku-san.
Gaku nodded.
Show me.
Miyako scrolled through the tablet screen and began to speak quietly.
Until half a year ago, my brother was a normal streamer. He mostly did casual talk and sang songs, and his viewers were all gentle people. I loved his streams too.
On the tablet, an archive of Minato's past streams appeared. It was the Minato Gaku knew. Bright, loud, a bit of a goofball. Chatting happily with his viewers.
But four months ago, he suddenly changed. The content became provocative, aggressive—stirring up the viewers. His language got rough, and even his laugh changed.
Miyako played a video file.
A dim room. Minato's face illuminated by pale blue light. The same footage Gaku had seen at the internet café that night. But this time, the audio came through clearly.
Do you guys really like me? No, you don't. You're just praising me because you give me money. ...Hey, right? Come on, be honest. You can't live without me, right?
Minato's voice sliced through the café's silence.
Gaku felt sweat seep into his palms.
This wasn't Minato.
The Minato Gaku knew was a man who treasured his viewers. At the end of every stream, he'd bow his head and say thank you for watching. How could a man like that—
He streamed this from two to four in the morning. Every day, at the same time. When that hour came, my brother would lock his door so no one could get in.
Miyako's voice trembled faintly.
One night, I was passing by my brother's room and caught a glimpse of his computer screen. And there it was.
Miyako switched the tablet screen.
A screenshot appeared. Probably taken through the gap in the door, capturing Minato's computer screen. The image quality was rough, but the text was clearly legible.
〈Nocturne〉
And below it.
〈Personality Overwrite Module — Application Progress: 62%〉
Gaku stared at that number.
62%.
(It's not complete yet.)
Minato's personality hadn't been fully rewritten. At 62%, the remaining 38% was still Minato's. There was still time. Gaku held the same faint hope in his chest that he'd felt that night at the internet café.
Miyako-chan, when did you take this?
Two weeks ago. ...But after that, my brother stopped coming home.
Miyako bit her lip.
A single email arrived on my brother's phone. A "Deep Streamer Promotion Notification." When I saw it, I knew instinctively. My brother hadn't gone missing. He was taken.
Deep Streamer.
The moment he heard that word, something cold ran down Gaku's spine.
(Deep Streamer... someone close to the core of Nocturne, then.)
Gaku desperately organized the information Miyako had gathered in his head. The emotion amplification filter, the dependency induction algorithm, the personality overwrite module. And the Deep Streamer. This girl, still a high school student, had nearly single-handedly reached the core of Nocturne's technological framework.
Miyako-chan, you researched all of this by yourself?
Yes. Reading articles online, infiltrating streamer communities. I tried not to do anything dangerous. ...But I was desperate to save my brother.
Gaku was speechless.
This girl had stepped deeper into this darkness than he'd imagined. And she'd done it alone, without relying on anyone. Gaku keenly felt that he still understood noth
Novelia is an AI-powered platform to read original light novels and fan fiction, create your own in just a few taps, and chat with the characters. New, illustrated episodes arrive daily — free to start.