During the Warring states era, the Assassins worked to prevent the spread of the Templar influence in Japan, spread by Jesuit missionaries such as Francis Xavier and Alessandro Valignano. While the Templars recruited people such as Mochizuki Chiyome and Uesugi Kenshin, the Assassins recruited individuals from the ranks of the ninja and samurai, such as Hattori Hanzō and Yamauchi Taka. Over the years, the Japanese Assassins supported the ascension of the daimyo Tokugawa Ieyasu, eliminating his rivals along the way.
Following the Great Purge of 2000, the remaining Japanese Assassins were present in Osaka. In 2013, their headquarters was attacked by the yakuza faction known as Onmoraki-Gumi, resulting in the death of the Japanese Mentor Kenichi Mochizuki. His wife, Saeko Mochizuki, led an attack on the Onmoraki-Gumi in retaliation, and took over the organization, subsequently using it as a front for the Assassin activities and leading as the Japanese Brotherhood's new Mentor.
- Hattori Hanzō
- Hattori Masanari
- Mochizuki Kenichi
- Mochizuki Saeko