The following contains spoilers for Sonny Boy Episode 2, "Aliens," now streaming on Funimation.
In the anime series Sonny Boy, there was one surprising moment where the solution for the lack of a currency exchange system was introduced as a digital app called Hyo-Ryu-Coin. Hyo-Ryu-Coin takes inspiration from cryptocurrency systems similar to those of Bitcoin and Ethereum.
Sonny Boy is a mystery anime about thirty-six high school students vanishing into different worlds where there are absurd environmental rules keeping them from getting back to their own. The students suddenly gain supernatural powers such as the ability to fly or to invent objects with just a thought. Sonny Boy is an original series produced by Madhouse studio and aired from July 16, 2021, to October 1, 2021. Shingo Natsume, who also directed One Punch Man and Boogiepop was Warawanai (2019), was the director for the 12-episode series.
In the second episode of Sonny Boy, the high school students disappear into a world where the rules are that if you receive or take something and don't pay, the object burns and perishes in blue flame. Not having any assets of their own in that world created a problem. They could not create a fair exchange with any objects and this caused everything they touched to eventually burst into flames.
In the last moments of Episode 2 of Sonny Boy, Hyo-Ryu-Coin is introduced by a student named Rajdhani, as a digital currency app using the internet to open ledgers and manage asset transactions. Rajdhani has the ability to design and program things into existence, enabling him to create gadgets and tools to help them survive in the different worlds.
Rajdhani's Hyo-Ryu-Coin app functions by QR code transactions to settle electronic currency trades with others on the island, or with the island itself, regarding transactional exchanges. Hyo-Ryu-Coin allowed them to trade electronic cash and also to trade things on digital loans.
It is unknown whether the cryptocurrency system of Sonny Boy had a limited or infinite supply. However, the development of the system demonstrates a real-world solution to a world without a proper financial or barter system, as the students were unable to take anything that they didn't initially own. As long as they had a currency system, the values of objects or exchanges could be determined regardless of the supply of electronic currency they had.