The logline describes a vague plot because the inciting incident "...rises to become a samurai..." seams like a long process initiated by the main character rather than a sudden even which changes the MCs life and forces him to take action. It seams like the "real" inciting incident that motivated him to want to become a samurai would have happened before hand, what was it?
The second big problem is the goal is not clear, what does "...the challenge of a corrupt general..." mean specifically? What will it look like? Best to be specific about the goal and what he must achieve?
Lastly what is at stake? What could make this a compelling story is a clear definition of what he stands to lose if he fails and gain if he succeeds.
Hope this helps.