Well this is stupid, Japan itself still has an emperor from the imperial family, plenty of countries still have nobility and many still also have class systems (openly like India and their casts) or simply socioeconomic status
Sure, but the mobile class systems of modern day and the extremely-strict class systems of places like Imperial China, Feudal Japan, and Medieval Europe are very different. For one thing, we have a basic idea of human rights incorporated into a defined set of laws that are at least partially enforced. Most of these class-based societies had variable punishments with strict enforcement and little sense of innate rights.
So a thief today will likely take a plea deal and spend a defined time in jail or pay a bribe. A thief in Victorian England could have his hand cut off, be straight up executed, or let off with a bribe. A thief in Han China is unlikely to be caught, but the punishment varied from the cruel and bizzare (if against a superior) to completely unpunished (if against an inferior). And so on and so forth. Punishment was strictly tied to your class as a person, not loosely connected to socioeconomic status as it is today.
Also am Indian, and can confirm we do not have an existing caste system. The scars remain, but the system is long dead.