Did the fake shogun agree to be killed by Hattori Zenzou?
The double was Kagemaru, and he was fully prepared to die for Shige Shige's sake. In episode 302, he says:


  "I, Kagemaru, wouldn't be here if he(Shige Shige) hadn't saved my life
  back then. Use it for his sake".


So yeah Hattori and Kagemaru were both in on the plan.