Born in Chenôve, near Dijon.

My grandmother Marie lived in a small château called La Sérrée, with red shutters, a vast park, a river, pontoons, a grotto, and a belvedere overlooking the forest. The library overflowed with books — I once found a grimoire of magic spells in it. She kept cats, sometimes as many as fifty-six. Both she and my mother were members of Mensa.

My mother's machine. She was a single mother and would let me play with the Sinclair while she did other things. She wrote games for me—a musical keyboard, a labyrinth with custom font sprites, and others. I started by tweaking her code: making myself walk through walls, or more often just breaking everything. The Spectrum's BREAK key let you pause any running program and inspect its source. I think I enjoyed breaking out of the rules and seeing the code more than playing.

On the Spectrum I built a messaging system where users could create mailboxes and send messages to each other. I also reproduced our house alarm system—it had a keyboard where codes activated zones and configured schedules, but I was forbidden to touch it, so I emulated the whole thing on the Sinclair. I remember struggling briefly with the step from FOR/READ/DATA to DIM arrays—my first encounter with the concept of structured memory. I was surprised by how short the musical keyboard code was—it just played a sound with the frequency being the key's ASCII code multiplied by some value. I spent ages tweaking colours and being frustrated at the Sinclair only allowing two colours per cell.

I moved in with my grandmother in Dijon and started CP (cours préparatoire). No computer around anymore—a jarring change from the Spectrum days.

I did CE1 and CE2 in a single year at the Enseignement par Petit Groupes in Dijon, effectively skipping a grade.

CM1 at the Enseignement par Petit Groupes in Paris, living with my mother. Her apartment had a 286 I wasn't allowed to touch, and later a Macintosh Plus. HyperCard was a revelation—cards, stacks, buttons, scripts. An entirely different way of thinking about software: event-driven, interactive, visual. I didn't understand much HyperTalk (no documentation), but the experience of building interactive systems stayed.

Back to Dijon for CM2. Around this time I got my hands on an Amiga 500 at my grandmother's. After the Spectrum's constraints, the Amiga felt like a different universe—proper graphics, multitasking, and a real operating system.

I remember taking the RER across the Paris banlieue to a library, where I photocopied an entire book about Amiga internals. I wanted to know what every function in every library did. I discovered you could hook library functions by overwriting the jump table offset to your own address—because the Amiga shared one flat address space across all tasks, with no memory protection. I upgraded from Workbench 1.3 to 2.04, expanded storage with an Iomega Zip drive (which promptly lost most of my work to the infamous click of death).

My mother upgraded from the old 286/Macintosh to an actual modern PC—an AMD K6-II running Windows 98. More importantly, we got ADSL with Wanadoo and their weird green modem. After years of exploring machines in isolation, the internet opened a whole new world. Everything I'd been doing alone suddenly connected to everyone else doing the same thing.

Free.fr had just launched in France and offered free web page hosting. I built my first homepage there—earliest pages dating to November 1999. It included an Amiga Zone where I published disk copying tools I'd written, a MOD plugin for Winamp, and a collection of my favourite Amiga tracker modules. The rest of the site was pure late-90s teenager: Half-Life, ICQ, the Shadoks, and FSLT—a guild I was in playing Counter-Strike beta 4. Years of building things in isolation on the Spectrum and Amiga, and now I could share them with the world.

I experimented with building a real-time chat in the browser using hidden iframes that loaded PHP scripts returning JavaScript code. The server would push updates by generating <script> tags that called functions in the parent frame. This was essentially what the world would later do with XMLHttpRequest and JSON—except JSON didn't exist yet. When Firefox came out, I would use .toSource() to serialise objects into JavaScript notation, years before Douglas Crockford gave it a name.

Moving from the private school system to public caused my file to be lost. I was supposed to attend Lycée Camille Sée, but with no file there was no room. The administration had to find another place, which took time—and in that gap, in September 2000, I launched ookoo.org, my own hosting service. It started with web hosting, then I ran an IRC network on top of it. The domain is still mine today. When a spot was finally found, I did half a year of seconde générale at Lycée Claude Bernard before things fell apart. Another year lost—but ookoo.org kept running.

Two years (seconde and terminale) at Louis Armand. Obtained the BEP and CAP in electrical engineering. The formal education was over. Around this time I also stopped explaining that my prénom d'usage was actually Robert—my third first name—and just let people call me Mark. I was ready to move on to what I'd been doing since age three—just this time, someone would pay me for it.

As I built things with Linux that people found magical, I adopted the name MagicalTux — a play on the penguin mascot. Years later I'd start a blog called A Wonderful Life in a Magical Tux, but the handle came first and would follow me into everything after.

Launched a French Ragnarök Online private server on the ookoo.org infrastructure. The goal was to let French players who couldn't access the international servers discover the game—whether because of the cost, the language barrier, or the lag. I wrote the patcher in Blitz Basic for Windows—the same language I'd learned on the Amiga—handling downloads and updates to the Gravity GRF file. The login and character servers ran on versions I rewrote entirely in PHP — which outperformed the original C implementations, since those used a busy loop around listen() instead of select(). FRO would run for nearly four years, building a community and teaching me as much about managing people as about managing servers.

First payslip from a small game company, dated October 2003—addressed to my mother's apartment, where I was living at the time. She had moved to a smaller place after collège when the owner of the old apartment changed hands.

For a while I lived with friends from manga4all, an internet group I knew through the IRC network. The manga and anime community, the servers, the people I met online—it all overlapped. This was the world I'd built for myself while the school system had no idea what to do with me.

Moved into my own place—a tiny 8 m² apartment in Alfortville. Over a year of independence: working, running FRO, and figuring out the rest.

Flew to Japan for the first time with Méko, a friend who had created Pinpin Lelapin, Dating Sim, and Studio Tanuki. We were there to represent MangaPop at the Tokyo Anime Fair. I stayed in a capsule hotel and took hundreds of pictures. A brief trip, but enough to plant the seed that would eventually pull me there for good.

During the 2005 suburb riots, I coordinated transport logistics on IRC for people stranded across the city — years before Twitter existed. Grassroots civic tech, improvised in real time.

A brief stint at Fotovista (Pixmania), lasting about three months.

Joined Nexway, a digital distribution company. I'd stay connected to this company for a long time—leaving a few months after moving to Japan in 2009, but continuing to work with them through my own company even to this day.

Made Aliyah to Israel with the idea of launching a cybersecurity venture. The project didn't survive the reality of the region—the 2006 Lebanon War had just ended and the security situation made it untenable. I returned to France after roughly nine months.

When French Ragnarök Online launched officially, the reason for FRO's existence disappeared. After nearly four years and countless people passing through, I shut it down. "Gérer FRO m'a permis d'apprendre énormément, et fut également une expérience inoubliable, que ce soit sur le plan technique ou le plan humain."

Featured in Suck My Geek, a Canal+ documentary exploring geek and otaku culture in France. A brief moment under someone else's lens.

Returned to Japan, this time with a group of friends from the otaku community. Tokyo, Akihabara, the whole circuit. The pull was getting stronger.

My grandmother Marie died at 74. We had not spoken since a falling-out during my lycée years. She left me her cat — Tibane, who would later lend her name (with an extra n) to the company I founded in Tokyo.

Nexway was acquiring a Japanese company, CoGen Media (later Degica), and I convinced the president to send me. Third visit to the country, but this time with no return ticket. In my luggage: my cat Tibane, t-shirts for the next three decades, my computer equipment, and a determination to never turn back. I settled in Kugayama, a quiet residential area in western Tokyo.

Founded my own company, a server hosting business named after my cat Tibane—with two n's, so the cat would keep her feline identity. Tibanne would become the vehicle for everything that came next.

About six months after founding Tibanne, a friend and client introduced me to Bitcoin because of payment difficulties he was having from abroad. I dug in immediately. The concept was extremely well designed—a decentralised system where the mechanism itself was the trust layer. I created the Bitcoin Wiki — Wikipedia was censoring cryptocurrency content at the time, so I set up a dedicated MediaWiki instance that became a central resource for the community and still runs today. I mined coins in the evenings; one night I earned 50 BTC in a single session. Tibanne became the first company in Japan to accept Bitcoin payments.

Jed McCaleb had originally built Mt. Gox as a Magic: The Gathering card exchange site before pivoting it to Bitcoin. In late 2010, 80,000 BTC were stolen from the exchange—sent to what would become the infamous 1Feex address. That hack is what triggered Jed to hand me the server credentials. I couldn't afford to buy the exchange, so he proposed I simply take over operations. Mt. Gox became a subsidiary of Tibanne. At the time, it had about 3,000 users.

Ten days after taking over Mt. Gox. I was in Shibuya when the ground started shaking. Sheltered in a nearby temple, helped strangers make phone calls, then walked home across Tokyo. Tibane was safe. The French Embassy organised evacuation flights, but my life was here. I stayed.

Exactly two years after my arrival in Japan. An attacker gained access through Jed's old admin account via SQL injection, manipulated the price, and triggered a mass sell-off. I shut everything down, rebuilt the system from scratch, rolled back the fraudulent transactions, and publicly moved the remaining 424,242 BTC to prove they were still there—a nod to the answer to everything.

Mt. Gox grew from 3,000 users to over a million, becoming the world's largest Bitcoin exchange — at its peak handling around 70% of all Bitcoin transactions globally. About 60 employees in Japan, another 100 in India. The Bitcoin price went from roughly a dollar to over a thousand. Coverage in Time, Forbes, and everywhere else. WikiLeaks started accepting Bitcoin donations. Tibanne's automated hosting had unknowingly served a Silk Road–related site; I was investigated as a possible DPR suspect for two years before being cleared. I acquired Shade 3D, a 3D graphics company, to diversify beyond the exchange. I was building a Bitcoin payment terminal and planning a concept café in Tokyo where customers would pay in BTC — the premises were ready when everything collapsed. Three years of building, firefighting, and trying to keep up with something growing faster than anyone had planned for.

As Bitcoin went mainstream, regulators scrambled to categorize it. In March 2013, FinCEN classified virtual currency exchanges as money services businesses, requiring federal licensing. Two months later the Department of Homeland Security seized $5 million from MtGox's US subsidiary account based on an affidavit by Secret Service agent Shaun Bridges — who had himself used MtGox to launder bitcoins stolen from Silk Road, and was likely trying to destroy evidence. Bridges was later convicted of corruption and theft. Banking relationships crumbled one after another — HSBC Hong Kong closed the account without returning the balance, Mizuho asked us to leave. Every few months: a new bank, a new jurisdiction, rules that didn't exist yet.

The full damage came into focus: approximately 850,000 bitcoins missing, drained gradually over years through compromised keys and transaction malleability exploits. I suspended withdrawals on February 7. A crisis document was drafted and shared confidentially with potential investors, then leaked online. I resigned from the Bitcoin Foundation board. By February 25 the site went dark. Three days later I would be standing at a press conference.

Mt. Gox filed for bankruptcy protection in Tokyo. At a hastily arranged press conference, I acknowledged the disappearance of 850,000 BTC and apologized. Nobuaki Kobayashi was appointed as bankruptcy trustee by the Tokyo District Court. Two weeks later, my lawyers disclosed the existence of 200,000 BTC I had stored separately in cold wallets. What followed would take a decade to resolve.

After the bankruptcy, death threats appeared on Twitter: people promising to hire someone to end my life. Jake Adelstein, the American investigative journalist based in Tokyo, began covering the case. He initially suspected I was guilty — but after digging in, concluded I was a victim of external hackers. He would later visit me in detention, bringing manga and a book on Zen Buddhism.

Arrested by Japanese police on charges of embezzlement and data manipulation related to Mt. Gox. Tibanne had already declared bankruptcy earlier that year. Held at Manseibashi police station near Akihabara. In November, declared personally bankrupt. In December, transferred to Kosuge — the Tokyo Detention House — for pre-trial detention. Solitary confinement, seven square meters, lights never fully off. I filled notebooks analyzing the 20,000+ pages of case documents.

In January I had obtained a calculator — a rare exception for detainees — and spent weeks cross-checking the prosecution's financial claims against 20,000 pages of accounting records. My calculations showed the numbers didn't support their case; the prosecution had to revise their approach. Freed on bail on July 14 after nearly a year in detention. Family, friends, and supporters pooled the bail funds. Conditions: forbidden from contacting approximately 30 people connected to Mt. Gox.

Personal bankruptcy, reputational damage, an ongoing trial — and yet, code. I contracted with the Japanese government to build a website designed to withstand attacks; it was never breached. I founded Echelle, a company focused on entertainment and anime production, with content broadcast on Japanese television. Together with Kim Nilsson and other former MtGox users, I continued tracing the stolen bitcoins through the blockchain to wallets linked to the BTC-e exchange.

Trial began at the Tokyo District Court. Charged with manipulation of electronic data and breach of trust. The core question: how I had handled the 80,000 BTC deficit inherited from before my takeover. As Bitcoin's price rose, the gap widened. I had converted the BTC debt into dollars through automated purchases — the mechanism later identified by researchers as "Willy Bot." The prosecution called it data manipulation. The defense argued it was a protective measure to keep the exchange solvent for its users. I pleaded not guilty.

Two weeks after my trial began, Greek police arrested Alexander Vinnik at a beach resort, acting on a US warrant. Vinnik was charged as co-administrator of BTC-e, accused of facilitating over $4 billion in criminal transactions. The US indictment explicitly linked him to the theft of bitcoins from Mt. Gox. Kim Nilsson and the WizSec team had spent years tracing the stolen coins to Vinnik's wallets — their independent investigation now aligned with the official case.

Under Japanese bankruptcy law, creditor claims were valued in yen at the date of filing. Bitcoin's price had risen enormously since then — meaning all claims could be repaid in full, with a large surplus going to the shareholder. That was me. In April I posted an open letter on Reddit: I did not want that money. I advocated for civil rehabilitation, a process where creditors would receive their fair share at current market value. In June, the Tokyo District Court approved the conversion.

Acquitted of embezzlement and breach of trust. Found guilty of manipulation of electronic data — sentenced to 2.5 years, suspended for four. The prosecution had requested ten. In a system where the conviction rate exceeds 99%, a suspended sentence with acquittal on the primary charges was as close to vindication as the Japanese legal system typically allows.

Founded Karpeles Lab. A new company, a clean start — applying everything the previous decade had taught about security, infrastructure, and what not to do alone.

The US Department of Justice publicly named Alexey Bilyuchenko and Aleksandr Verner — two Russian nationals accused of stealing 647,000 BTC from Mt. Gox between September 2011 and May 2014. Bilyuchenko was also charged as co-administrator of BTC-e alongside Vinnik. Kim Nilsson, who had spent nearly a decade tracing the stolen coins, confirmed the indictment aligned with his findings. After nine years, the thieves had names.