Uses the dice-roll and skill mechanics of tabletop role-playing games, but has nothing to do with the Cthulhu Mythos. The main setting is the Detective Conan world. To be clear, there is no Cthulhu Mythos in the Detective Conan world. The timeline is a closed loop.
Examples:
At a fixed target 100 meters away, he rolls a critical failure. The bullet ricochets off the metal frame and nearly hits Gin. Gin: "..." (draws his gun)
A victim screams in the middle of the night. The police come by first thing the next morning to ask questions. Kurojie, who slept like a log: "…" Right, I must have failed my Listen check. I didn't hear a thing.
Seeing a crime scene: SAN check, 1d3 loss. Repeat until he gets used to it.
Someone taps him on the back. If his SAN is low, he loses SAN. If he's fine, nothing happens.
Kurojie Yiyue is an "ordinary" gamer who was persuaded to download a full-dive CoC tabletop role-playing game. He finished assigning his points and entered the loading screen, then everything went black.
"Welcome to the game... bzz..."
He thought it was just a game, so he did whatever he wanted. That is, until he saw the bereaved relatives of the dead sobbing uncontrollably. Feeling a little overwhelmed, he tried to log out and order some crawfish, only to discover there was no logout button.
After giving it some thought, he confidently decided that completing the main quest would send him back to his original world. So he ran around looking for Cthulhu Mythos events.
But then he discovered that this world might not have a Cthulhu Mythos system at all.
It's purely a Detective Conan world.
After moping around for a while, he decided to turn over a new leaf and be a good person.
Conan: "Huh? Say that again? What are you?"
Kurojie Yiyue: "I said I'm actually a good person." (with an earnest expression)
And so...
Langley, Scotch, and Whisky from the Black Organization
(Glenlivet Scotch Whisky)
are all mentally unstable lunatics who often mutter to themselves. They regularly hit their allies by mistake during missions.
The elementary school art teacher is a mysterious fellow.
The police academy classmates vanish without a trace after graduation.
A member of the bomb squad has a childhood friend who went missing ten years ago.
Could Gin actually have a soft side?
The protagonist acts with the reckless abandon of a fourth-dimensional disaster early on, but reins himself in later.
Of course, it's an indulgent, feel-good story with no official romance pairing. There might be one-sided crushes.
The whole police academy group gets both saved and put through the wringer.
The timeline is a closed loop.
Gin isn't entirely loyal to the Organization.
The protagonist notices something strange early on, but doesn't want to think too hard while playing the game (crossed out) and thinks a lot instead.
Theme: Stay true to yourself.
