Yaminobu
The Yaminobu was a pro-Shogunate onmitsu group tasked with assassinating key members of the Ishin Shishi during the Bakumatsu. While they targeted several high-profile people, including Katsura Kogorō, their penultimate battle and near-annihilation came when they set themselves against the Hitokiri Battōsai in December of the first year of Genji (1864).
All trained in the mysteriously warped Binding Forest, the members of the Yaminobu are all particularly adept at striking from the shadows and proudly use cunning in their tactics when their combat abilities fail them. Within their home territory of the Binding Forest, they employ special strategies to ensure that, for each of their number who is defeated, the enemy is weakened in turn.
In spite of the deaths of its leader and chief members at the Binding Forest against Battousai, the Yaminobu had managed to survive into the Meiji era, but has lost its influence and are reduced to being mercenaries-for-hire.
Members
Murakami: A man that used dual katana chained together. He faced off against Battosai after the latter left a restaurant, but was killed with one of his own blades.
Nakajō: Best friend of Otowa Hyōko, from whom he acquired his 'Chusen'. He would be the first of the group to fight Battosai in the 'Binding Forest'. In the manga, after shooting Battosai with a dart from the 'Chusen', he gets his arms cut off at the elbows, runs into a cave, and sets off an explosion that temporarily takes away Kenshin's sense of hearing, killing himself in the process. In the OVA, Battosai impales him with his katana, and he activates the explosion as he dies. His death is later used by Otowa as an excuse to go after Kenshin.
Sumita: A large, soft-spoken man, who fights Battosai alongside Yatsume. He uses his axe to chop branches off of trees, from behind which Yatsume strikes. In the manga, after incapacitating his partner, Battosai cuts Sumita's legs off at the knees. Sumita then detonates a charge that temporarily blinds Battosai, killing himself.
Yatsume Mumyōi: The only surviving member of the Yaminobu. While fighting Battosai, the samurai used his katana to tack Yatsume's hand to a tree, and saw his true form in the process. Yatsume swore revenge for his clan, and joined Enishi's Jinchuu to exact it.
Tatsumi: Leader of the group, and Jutsu-Shiki Muteki-Ryu master to Inui Banjin. He relies on brains as much as body, formulating the strategy to use Tomoe to create a weakness for Battosai and the set-up of bonds in the 'Binding Forest'. When he fights Battosai, he chips away at his strength, making him physically weakened. He goes in for the final strike, but is blocked by Tomoe, and is cut down by Kenshin. His death is later used as an excuse by Banjin to join the Jinchuu campaign.
I'izuka: An Ishin Shishi traitor, who reports Battosai's status to the Yaminobu. He is killed by Shishio Makoto.
Kubota Asahi: A war orphan raised by remnants of the Yaminobu. She was later loaned by them to Shishio Makoto's organization. After managing to gain her freedom, she's currently staying at the Kamiya Dojo along with Hasegawa Ashitarō and Inoue Alan.