I Use Life as Currency

A pound of pork is worth 2 hours of life. If you call a taxi, you need to pay 1 hour of life as the fare. This is a world where you can only live until you are 28 If you want to continue living, you need to earn your lifespan by working or hunting monsters. The good news is that when all citizens reach the age of 28, their physical functions and appearance will be permanently fixed on this day. Even better news, if you can keep earning lifespan to extend your life, then you can achieve another kind of immortality.