To kill Kichizo, Taizo and Manzo Mamushi without being seen nor killing guards in Silent Death in the Ghost of Tsushima climb up the side of the rocks and over the fence. Climb up the ladder and onto the house ahead avoiding any guards.
Squeeze through the window into the house and assassinate Taizo. Go out the front of the house avoiding any guards and down into the tall grass.
Go all the way to the back of the area and assassinate Manzo. Go towards the stables near the house and go around them on the left avoiding any guards.
Climb the nearby house, squeeze through the window and assassinate Kichizo. Climb the ladder and go out the back of the house, jump to the nearby roof and back over the fence.