Photo/IllutrationSmartphones and laptop computers confiscated from the residence of an 18-year-old who is accused of stealing about 15 million yen ($134,420) in cryptocurrency (Yohei Kobayakawa)

  • Photo/Illustraion

An 18-year-old stole about 15 million yen ($134,420) in cryptocurrency last year from an online storage site using a glitch, saying that he felt like he had discovered a secret trick that no one knew, police said.

The teen from Utsunomiya, Tochigi Prefecture, is suspected of computer fraud as well as violating the organized crime punishment law by concealing criminal proceeds, Tokyo metropolitan police said March 14.

The suspect is accused of swindling a total of 97,000 Monacoins, worth about 15 million yen at the time, from Monappy-managed accounts between August and September last year. Police said he admitted to the allegations.

He is believed to have transferred most of the cryptocurrency to anonymous accounts on an overseas cryptocurrency exchange.

Monappy, an online crypt-currency storage service, has since suspended operations.

The teen acquired dozens of gift codes for Monacoins at an event in Tokyo's Akihabara district in August last year and apparently started to wonder if he could make multiple use of the one-time-use codes.

While he was waiting for one of the codes to process, he tapped the redeem button several times in frustration and discovered that he could make multiple withdrawals using a single code by repeatedly pressing the redeem button over a short period of time.

Exploiting the glitch in the transaction system using the gift code, he hit the button a total of 8,254 times using his smartphones and laptop computers, making 642 transfers, far more than the 133 times that the gift codes, including the ones from Akihabara, allowed.

"It was thrilling to see my balance increasing," the young man was quoted by police as saying. "I felt like I found a secret trick and tried to get all the coins, as if I were playing a video game."

He reportedly used several tools to make the transactions anonymous and keep his identity secret.

Japanese cryptocurrency exchanges have faced a number of major thefts recently, including the hack of Coincheck Inc. to the tune of 58 billion yen in January last year, and another against Osaka-based Tech Bureau Corp.'s Zaif exchange the following September for cryptocurrency valued at 7 billion yen at the time.

The case involving the 18-year-old is the first in Japan in which a hacker has been prosecuted over cryptocurrency theft, police said.

(This article was written by Chihiro Ara and Chihaya Inagaki.)