Rain soaks Koji Takada’s shoes as he races down a neon-lit alley, lost in thought. The city never rests. Sirens wail; lives go on, but questions grow each day he’s left with too few pieces. Why can’t we put the whole story together?
This isn’t a big city detective story set somewhere safe. It’s the walled district of Obsidian District–a place where secrets fester. Girls vanish at dusk. Old cases collect dust, and people stop asking too soon. Koji brings his battered notepad everywhere because someone must write it down. He can’t sleep until another case finds its end. That’s what keeps him going, even when things get ugly.
His sister Mio vanished three years ago. No note, no sign. Missing persons get their faces on tea cartons here for a week. Then—it’s silence. Koji’s main drive is clear: find out what happened to Mio, even if it costs him friends, jobs, and his health.
Arc Title: “The Phantom’s Mosaic”
It’s October. Gray sky, slow drizzle. Koji sits with former street hacker Reną Ishigami, who owes him a favor. “You know, Koji, nobody would care anymore,” she says dryly. He cuts her off: “You always say that, but I haven’t met the right person yet.” She lights a clove. Does he ever get tired?
Mio’s last known step was in a tunnel under Tenjin Station. Koji retraces it; Reną strings together vanished CCTV footage where frames skip at just the wrong moments. Ghost data, random static, patched together piece by piece.
Did you ever try to solve a puzzle with half the parts gone? Frustrating isn’t half of it. Yet Koji’s style: fill the gaps with humans. He walks the block. He talks to stooped shopkeepers, teens draped in LED wires, odd loners who cough up careful half-truths. Always polite—always asking what police won’t anymore.
By episode three, clues barely add up. A scrap of Mio’s scarf, found behind Seika Cinema. A coded luminescent sticker under a seat. There’s a name on it: Kano—code-slicer, gone since spring. It rings a new hope. Reną visits a shortwave ‘pirate node’ rumored to host missing kids’ signals, while Koji slow-walks block by block.
What do you do when nothing connects but you can’t give up?
On episode six, review logs suggest that five girls including Mio vanished along matching routes, same hours, split across weeks. Four reopened disappearances; four grieving families. Reną grits teeth: “Someone is doing this on purpose.” Koji replies: “You think someone benefits from us forgetting?”
Is there always a reason we let some cases drift into cold silence? Have you ever seen a case go cold, never to come back?
Soon, odd patterns appear on the mosaics that decorate old underpasses—tiles mismatched, forming a face seen only on moonless nights. Urban artists? Or silent signals? Koji shows cell snaps to an old painter in the market. The old man whispers, “I’ve seen the Phantom. People talk about the shape, but never what it hides.” Koji holds the snap up—tiles become words. The old man: “Those who seek too close often don’t return.” Koji heads into the tunnel alone that night, badge light flickering. 
A stray call warns Koji off, voice hiding in synth noise: “Stop tracing mosaics. They’re for the lost only.” Reną tells Koji, “Whoever’s building this leaves riddles to push you back.”
He spots odd drones, stray cats with tags, mismatched tiles leading underground. A floodgate skips open as if triggered for him. Heart pounding, Koji enters what feels like another layer of city beneath the noise—where sighs sound like old songs, and light falls the wrong way.
He calls out, “Mio! It’s me! Are you down here?” Footsteps echo, too many. A young voice responds: “Why did you wait so long?” The alley grows cold. Then—crackle, blackout. Episode 10 ends. Cut to black. Do you want to see if Mio is alive?
