A miserable end to any revenge story is one where the protagonist does not get his revenge at all. However, the GM of this story may choose to have both the protagonist and antagonist die. Or have the protagonist learn there is more to this story than just a kidnapping. Or, have the villain escape for a long term nemesis to hound and annoy Samurai X.
GM's should tailor the finale and the denouement to the player's style, giving some degree of control to the player who has endured so much to get to this point.
Some final questions.
Does Kajime survive?
Is the ceremony thwarted? If not, what happens?
Who else knows about this?
How does everything turn out for the other parties involved?
Are magistrates involved? Or does the story end inside a vacuum, with 99.9% of Rokugan never hearing anything of this tale?
Man on Fire