The Phantom ninja kidnap the shogun's nurse, Sakura no Tsubone, from within Edo Castle and hold her in the House of Night. They plan to kill her and leave her body in a public place as a laughing-stock unless she gets the shogun to make Sadanobu resign. However, Shūsaku remembers the way to the House of Night from when Hagenbō took him out to the Sainenji and so Shintarō is able to rescue Sakura.
