... is the western gate of the imperial palace, which was used to be Edo Castle. Hanzo-mon was named after Hattori Hanzo because he protected this side of Edo castle.
... is where Hattori Hanzo and his Ninja made their residence.
Sainenji Temple (西念寺) is Jodo Buddhism temple located in Yotsuya. It was originally established by Hattori Hanzo Masanari, known as the head of Iga Ninja, in 1590 for Okazaki Saburo Nobuyasu, the first son of Tokugawa Ieyasu. There are grave of Hattori Hanzo and Nobuyasu which built by Hanzo. Also, there is a spear of Hanzo in this temple.
Hattori Hanzo Masanari
... is the head of Tokugawa Iga Ninja and Koga Ninja. He served his lord Tokugawa Ieyasu for all his life, and because of his great sucess, he was also one of Tokugawa 16 great Generals. He was the master of spear, and known as "Hanzo, the Ogre."