The basis of wealth is land, because land produces food which can be used to feed your followers.
The Emperor owns all the land. He grants land to the clan lords to manage, who owe him loyalty in return. (Our city of Ryoko Owari Toshi is in Clan Scorpion territory.)
The real economy, then, is an agricultural one; production of food directly relates to the number of Samurai, artesans and peasants that a lord can feed and who therefore owe him loyalty in return.
To assist in accounting, each clan mints its own money. The value of this money fluctuates from season to season depending on the state of the crop.
It is extremely unlikely that a Samurai will know the value of money as it is considered women’s work, or the concern of traders to know such things. To question a Samurai on the cost of things or the value of their money is a grave insult as it implies that he might not know. Samurai do not conern themselves with such things as costs, instead paying whatever they think is fair for whatever they are freely offered as befits their station. Note: it is rude for a Samurai to give nothing, and the merchant who supplied the goods or services maintains meticulous accounts which are lodged with the lord for due consideration anyway.
Since each clan produces its own coin and the value of that money is related to agricultural production, exchange rates are constantly fluctuating. Each lord has a team of accountants to handle this, and there is a fortune to be made in changing money. Note that handling money in this way is considered pretty low on the social order by most decent people.
Administration and law
Each clan lord appoints magistrates to administer provinces, cities and districts. These officials are charged with collecting taxes and investigating crime. There is a well developed hierarchy of offices and authorities down to local deputies and including such specialists as pathologists (since touching the dead is considered unclean and is the work of ‘eta’, or untouchables).
Each clan has its own laws and when in that territory you must obey them.
The Emperor also maintains a system of magistrates to investigate and punish crime when the matter affects more than one clan or is interclan based. Imperial magistrates have authority above local magistrates but seldom interfere with local matters – it would create a diplomatic incident if they did.
A disarmed society
This is not quite true as many people are armed and weapons can be easily fashioned. However, the sword is the signature fashion of the Samurai who are a specific identified class – much like a European knight in some ways.
There are no swords shops that you can wander in to and pick up a sword from a rack. Swords are made for each Samuari under specific instruction from the lord. Other weapons may be specialised military forms or, more likely, are contempuously classified as peasant defense.
This holds true for many things that are made by craftsmen and can never be simply bought and sold. This may sound strange to a western high fantasy (based on an American ‘wild west’ frontier model), but I have a deep suspicion that this model was probably fairly close to the situation in historical Europe. European knights were pretty jealous of their status as well.