There are vids of people beating them at sl1 on NG+7. They use R. Tearstone but they are also using an elemental weapon. You don't need to button mash, just attack so you have enough stamina to dodge when they attack. Basic rules still apply to the fight.
If you build your shop in front of an arrow trap, sometimes you are going to get shot by an arrow.
*places poison rice bowl and creeps back into the shadows*
I dunno about the bowl part, but Poison Rice was my best friend in Tenchu. With some fast footwork you could execute the target before they had time to consume the rice, and then use it again. Sadly Alluring Skulls just aren't the same.
"I'd rather betray the world than let the world betray me." -Cao Cao