Mukotsu

was a member of the Shichinintai. He was a master of poisons of sorts and utilized a number of different poisons and gases to attack his enemies. Due to his elderly appearance, he is considered to be the oldest of the Shichinintai; he is also the second weakest member.

During the story
Mukotsu first appears during a battle between the Inuyasha group and Jakotsu, releasing his poisonous gases into the valley where the battle is taking place as a way to allow Jakotsu to escape quickly and safely. Later on, Jakotsu comes across Mukotsu in the shallow forest where he is mixing up some potions and talking to himself. Mukotsu is instructed to go after Kagome Higurashi and poisons her near a little hut, dragging her inside and proceeding to try and marry her. He drapes a white blanket over the half-conscious Kagome and does a little marrying ritual, singing and holding her hands. He then gets on top of her, but Kagome thinks fast and stabs him in the throat. He becomes enraged, yelling that she doesn't love him because of his hideous appearance. Kagome listens but doesn't speak, and he slaps her hard across the face. He is about to kill her when Sesshōmaru suddenly appears and slashes Mukotsu across the back.

Mukotsu and Sesshōmaru leave the hut and go outside where Mukotsu pompously attempts to suffocate Sesshōmaru with his poisonous gases, but to no avail. When Mukotsu realizes that Sesshōmaru is impervious to his attacks, he hastily drops his weapons and cowardly hides behind the bushes, pretending to surrender. Sesshōmaru approaches more, but Mukotsu suddenly draws out another weapon and blasts more gas at Sesshōmaru. This time when he surrenders, Sesshōmaru kills him on the spot with one stroke of the Tōkijin. Meanwhile, Jakotsu has been watching the entire time and runs off with news of Mukotsu's death.

Mukotsu was very similar to Jakotsu in the fact that he was constantly looking for a potential partner, only in Mukotsu's case his "victims" were women. However, he couldn't stand rejection, mostly because of insecurity about his appearance. Any time a woman rejected his affections he automatically assumed it was because of looks, which was probably a large contributing factor. Another factor is that he always came on too strong.

Mukotsu had red circular markings around his eyes and near his chin.

Powers & Abilities
Mukotsu is skilled at making different kinds of poison for different purposes however when he got killed by Sesshōmaru, it shows that he has little experience in dealing with demons, although this could also be due to the fact that Sesshōmaru uses poison himself. He also seems clearly and completely unaffected by his own poisons, seen in his first apparition where he somewhat drank a bit of his own poison probably testing its efficiency (later, talking with himself saying "Yes, it's right!" as if saying the poison is right) meaning his mask is only for decorative purposes.

Trivia
Mukotsu
 * His tattoos mean Poison, referring to his use of poisons as his weapon of choice.
 * Mukotsu (along with Kyōkotsu), are the only two members of the Band of Seven who did not get their own individual theme music in the InuYasha Official Soundtrack. This is most likely due to the fact that they're both killed quickly after being introduced.
 * In the manga, when Sesshomaru appeared and attacked him from behind, Mukotsu's left arm was torn off.