From the Game's Introduction:
Your samurai has made some mistakes, the kinds of mistakes that other people get killed for making. Your samurai is trying very hard to atone for the past by living a life of honour. Your samurai is also trying to hide the past by pretending to be as honourable as possible. It's a combination of guilt and fear.
Just how honourable your samurai is trying to be depends on how wicked they have been in the past. When you create your samurai character you'll be asked to devise a number of secrets about the bad things they have done. Each secret gives your samurai one point of honour. Your character starts off with either two, three or four secrets so your character will have a starting honour score of two, three, or four.
Your samurai has good reason to behave honourably and will be reluctant to depart from the code. Every time you want your samurai to breach the rules of honour, or ignore an obvious opportunity to do something honourable, your GM may force you to make an honour roll.
For an honour roll, roll a single d6 and compare it to your samurai's honour score on your character sheet. If you scored lower than your character's honour then your samurai chooses the honourable course of behaviour dictated by your GM. If you roll higher than your samurai's honour then you are free to ignore the code and have your samurai do whatever suits you.
Every time your GM asks you to make an honour roll they will award you one Will Coin regardless of the outcome of your roll. You see, every time your samurai feels the code constraining and ruling them it chaffs away at something inside. Determination, resentment, and ambition start to swell, the same qualities that got your samurai into so much trouble before!