So, a "Toseinin" is kinda like a wandering gambler during the late Edo period.

These guys just drift everywhere and make a living by gambling. While they were basically hobos and social outcasts, they still had the traveler's dining etiquette – an iconic one being wrapping the fish bones from the fish they were served in a piece of paper, pocketing it, and throwing it away once outside the establishment.

The idea is that you don't leave any waste behind.