MONEY

Originally, the name I wanted to give to the cryptocurrency was G-coin, however this would force me to take an anticlimactic pause to explain that G-coin is a cryptocurrency and blah blah. That's why I decided at the last moment to use BITCOIN because everyone should already know what it is and I don't have to stop to explain it. The legal tender is CREDIT and I don't need to explain it either because this trope has already been used by other science fiction stories in the past.

English translation thanks by Bowman