#VtuberDisappearanceCase

2026/05/08 Update Ver2.0 Released
Added features for casual play.

This is a free mystery game where you investigate real-world websites.

◯ Prologue

Case Name
Case No.001 "Vtuber Disappearance Case"
Client
Vtuber "Ekato Yumemi" fan: Shun Nishijima (32 years old, male)
Investigation Details
1. Confirm the safety of Vtuber "Ekato Yumemi"
2. Investigate the talent agency "Phos"
Explanation from the client
"Ekato Yumemi" was active under the talent agency "Phos," but she suddenly stopped her activities one day. Then, a year after her last stream, I received a DM from her official social media account with the following content.

"
Please keep watch.
grandpasdedeux 85600512
https://phos.system03.jp/
"

Upon receiving this message, I believed she had been caught up in some kind of trouble and was asking for help. I contacted the agency and consulted the police, but the agency turned me away, and the police told me they couldn't act due to "insufficient evidence."
After that, I had no choice but to conduct my own investigation, but recently, incidents that made me fear for my safety have occurred, such as being followed by a stranger and having my home ransacked. Given this situation, I decided that it was too difficult for an amateur like me to handle, so I have requested this investigation.
Please investigate Ekato's safety and the facts that the talent agency may be hiding.

I have summarized the information I have obtained so far below.

・The URL above is the official website for the talent agency "Phos," and all pages and history related to "Ekato Yumemi" have been deleted.

・Entering "grandpasdedeux" into the search bar on the site displayed an eerie photo.

・There may be a security hole in the site's search bar, and it might be possible to access data or pages that are supposed to be private.

◯How to enjoy this game

1. Game Objective

   • Investigate real-world websites and aim to reach "Level 10 Confidential Information."

2. How to proceed

   • Find "keywords of interest" from various pages on the site and search for them on the website to access deeper pages (information).

   • Some documents contain hidden hints or information, and solving puzzles and thinking critically are key.

3. Features

   • Information is classified by confidentiality level from "Level 1" to "Level 10," and you get closer to the truth as you progress.

   • There are approximately 120 pages across the entire site, and there are no restrictions on investigation methods or time.

1. How to Enjoy

   • You can play alone or with friends and colleagues.

   • Proceed with the investigation at your own pace and uncover the truth.

   • If you get stuck, posting on social media with #VtuberDisappearanceCase might get other investigators to help you.

   • Since the difficulty changes depending on your abilities and the number of people, please use hints according to your playstyle. (Think of it as: look at a hint if you haven't made progress in an hour.)

   • If you are busy, you can also enjoy it via game streaming. (YouTube / Twitch).

2. Points to Note

   • There is no need to edit or analyze hidden links, source code, or files. Please deduce from the information visible.

   • There are no hints or information in the URLs. No modification is required.

   • Using crawlers (searching exhaustively) on lists or similar items may spoil the game experience.

   • There are no jumpscares or grotesque imagery.

   • Some words may have variations in spelling. Please try the candidates.

   • If you are not confident in your investigative work, please read this New Investigator Manual.

◯ About Hints

(Updated 2025/04/14)
Based on everyone's feedback, some corrections have been made.
I have made corrections to several areas where players were getting stuck systematically, so I think it will be easier to proceed smoothly.

The following are additional hints. Please use them as needed.
(There is a possibility of missing something, so please look at them in order starting from Level 1)
Levels 1-3
https://note.com/sim/n/ne19369fc288f
Levels 4-5
https://note.com/sim/n/n21583f918487
Levels 6-7
https://note.com/sim/n/n1da03e9ae07c
Levels 8-X
https://note.com/sim/n/n6e519669eb3b

◯ How to enjoy after clearing

I have written it here. Please view as appropriate.

◯ About this work

This work is a personal project created with inspiration from Daiyon Kyokai's Kagami no Tokushu Shonen Kosei Shisetsu. All of Daiyon Kyokai's games are very interesting, so if you haven't played them, please do.

◯ Update (2026/05/08)

Ver 2.0 has been released.
With the addition of new features, it is now easier to play more casually.
Main update contents:
・Implementation of history function: Added a history function. A list of viewed pages is displayed.
・Implementation of AI (AtamaIi) analysis function: Added a summary display button to each page.
・Other various adjustments and improvements: Various updates have been made.
If you prefer Ver 1.0 (Classic), click here

◯ Other / Inquiries

・I would be happy if you could share your thoughts on social media, etc.
・Regarding derivative works and fan art, please feel free to enjoy them as you like. I would be happy if you let me know. (Monetization is OK)

◯ Streaming Guidelines

I welcome the posting of videos/articles such as playthroughs and reports. Monetization and spoilers are also fine.
Also, if you are concerned about the game content, I can share materials for prior confirmation. (Since these materials contain spoilers, please refrain from viewing them if you are going to play the game.)
Furthermore, since there is a fair amount of text, I hope you will make use of auxiliary tools such asYomiage-chan.
I would be happy if you could enjoy playing it over multiple streams or by taking breaks.
(Added on 2025/02/07)
・I use music from YouTube in the game, but it is fine to play it during your stream. (Please consider it as royalty-free music.)
・The images for thumbnails are here.Please feel free to use them. If you need any other data, please let me know. Also, if it is something simple, I can create thumbnails for you.

If you introduce the game in a video on YouTube or similar platforms, it would be a great encouragement if you could include the links below.
Talent Agency Phos:https://phos.system03.jp/
SIM3 Account:https://x.com/sim_CF