The next part of the game will be play by email, or by forum actually at: http://diddysl5r.freeforums.org. This is the info the characters have in order to make a decision about what to do next
The Yasuki (the one in the papers) are a Crab family who deal in trade. To the point of being disgraceful in normal society (remember Samurai don’t deal with money normally). The Yasuki on the papers is likely doing the work for a higher ranking Crab.
Whoever made the decision to order these events to take place is probably higher status than you. This makes accusing them directly either impossible or pointless. You have no authority over someone of another clan and status generally determines who is right, not evidence. Accusing the Crab in charge directly will either get you laughed at or a Tetsubo in the face.
It’s not abnormal for clans to use merceneries to do dirty work but what they are used for reflects on the Samurai hiring them and therefore his clan.
Regardless of the Crab’s reasons for the attacks, someone will be in charge and they are using mercenaries against another clan, this is a clear reason for war since whatever he does is seen as his clan’s actions. The only ones who can punish him are the Crab or the Emerald magistrates if his superiors do not ask him to commit seppuku for his dishonor.
Should the Crab clan stand by him and not make it clear that he was acting on his own, not asking him to commit seppuku (or strip his rank and sending him to the wall), it is an act of aggression and would essentially mean war between the two clans. The Hare may not be as strong as the Crab, but they are not to be underestimated either, as they are very sneaky and can cause a lot of damage.
Feel free to ask me questions about how things work.