Background
In early April 2026, Kobayashi (a pseudonym), a client from Nagoya, contacted us about something that had almost been forgotten.
The problem Kobayashi faced
In October 2015, when Bitcoin was still in its early days, Kobayashi received a transfer of 0.5 BTC.
Ten years later, the private key for this address was nowhere to be found.
Kobayashi remembered creating the address, but memories of where it had been saved and what password had been used had become unclear.
Kobayashi’s difficult situation
- Assets: Approximately 0.5 BTC (worth approximately several million JPY)
- First received: October 2015
- Last transfer: April 2026 (with our assistance)
- Dormant period: More than 10 years
- Private key status: Completely lost, but potentially present on an old device or in a backup file
- October 2015
The address first received approximately 0.5 BTC, with no subsequent activity
- 2016–early 2026
The private key remained missing for 10 years as Bitcoin’s price continued to rise
- Early April 2026
Kobayashi asked us to carry out a technical recovery
- April 2026 (early)
Successfully located the private key and safely transferred the assets
Technical recovery process
Stage 1: Gathering clues and examining devices
We began with several detailed interviews with Kobayashi, trying to reconstruct how the wallet had been used in 2015.
Key clues
- The computer used in 2015 had already been discarded, but a file backup might still exist
- The client had used Bitcoin Core at the time
- The client remembered making a backup on an external hard drive
- The client remembered setting a password, but had completely forgotten its contents
Stage 2: Digital forensics and wallet file recovery
Kobayashi located an external hard drive that had been left unused for years. We performed a deep scan of the drive using the latest U.S. digital forensics technology.
A major discovery
We found an encrypted wallet.dat wallet file in an area containing deleted files!
This meant that an encrypted copy of the private key still existed, but recovering the password was necessary to access it.
Stage 3: Password recovery
Using the clues Kobayashi provided about password habits, we built an intelligent library of candidate passwords with the latest U.S. cryptanalysis technology.
Technical analysis process
- Uncovered password creation habits from 2015 through detailed interviews
- Analyzed common patterns in how people create passwords
- Used the latest U.S. GPU parallel computing technology
- Ensured computing speed through our own large-scale computing center
- Adjusted the strategy dynamically, prioritizing the most likely combinations
Successful password recovery
Early April 2026
Password recovered and private key fully restored!
Approximately 0.5 BTC, dormant for 10 years, was finally accessible again.
Safe transfer of the assets
Immediately after recovering the private key, we helped Kobayashi transfer the assets safely.
Transfer record
Date: Early April 2026
Amount: Approximately 0.5 BTC
Status: Safe transfer completed
The full address and transaction details are available for review at our office
- 0.5
- BTC recovered
- Several million
- Asset value in JPY
- 10+ years
- Asset dormancy period
- 100%
- Recovery success rate
Project results
| Item | Result |
|---|---|
| Recovered assets | Approximately 0.5 BTC |
| Asset value | Approximately several million JPY |
| Dormant period | More than 10 years (October 2015–April 2026) |
| Problem type | Completely lost private key and an encrypted wallet file |
| Technology used | Latest U.S. digital forensics technology + password recovery technology |
Fees
| Fee item | Details |
|---|---|
| Upfront fee | JPY 0 — completely free assessment |
| Data forensics costs | Covered by us |
| Computing costs | Covered by us |
| Technical costs | Covered by us |
| Success fee | Charged only after successful recovery — no fee if recovery fails |
Client testimonial
“I had almost forgotten about 2015. Bitcoin was still worth very little at the time, only tens of thousands of JPY, so I did not think much about it.”
“I replaced my computer several times after that and lost track of the backup files. I remembered them when Bitcoin’s price soared, but by then I could not find them anywhere.”
“I thought this money would never come back. But they found the wallet file on an old hard drive and even recovered a password I had forgotten myself.”
“When the transfer went through, I could hardly believe it. To get this money back after 10 years!”
“These bitcoins are now worth several million JPY. Thanks to their technical expertise, my investment from 10 years ago was not lost.”
Key factors in the successful recovery
Keeping old devices
Data recovery was possible because Kobayashi had kept the external hard drive used at the time
The latest U.S. forensics technology
Successfully recovered an encrypted wallet file from an area containing deleted files
Password pattern analysis
Built a library of likely candidates based on password habits from 2015
Large-scale computing resources
Tested password combinations at high speed in our own computing center
Technical advantages
The latest U.S. digital forensics and password recovery technology
- In-depth digital forensics and file recovery from areas containing deleted data
- Support for a variety of early Bitcoin wallet formats
- The latest cryptanalysis algorithms developed in Silicon Valley, U.S.
- Intelligent password prediction based on human behavior patterns
- High-performance GPU parallel computing
- Our own large-scale computing center, ensuring data security and computing speed
Applicable situations
We can help resolve the following problems
- Lost private keys for early Bitcoin addresses
- Wallet files that may exist on old computers or hard drives
- Encrypted wallet files with forgotten passwords
- wallet.dat file recovery
- Dormant addresses that have not been used for many years
- Corrupted or accidentally deleted backup files
Verification of authenticity
This report is based on a real case
All data can be verified on the blockchain.
Full addresses, transaction hashes, and other details are available for review when you visit our office.
To protect the client’s privacy, we do not publish sensitive transaction data online