He is considerably softened in the anime, where he had merely an inferiority complex about his looks and delusional casanovic fantasies about marrying Kagome.
Mukotsu made his debut in the 237th chapter of the manga and the 103rd episode of the anime, sending a cloud of poisonous fog onto the battlefield Inuyasha and Jakotsu were fighting on to allow the latter a quick escape. Jakotsu later meets up with him a deep part of a forest, where he's testing the potency of the poisons that he's brewing. Both discuss Inuyasha's group and express desire for a certain member of the group for their own; Inuyasha and Kagome respectively. Jakotsu promises to keep Inuyasha busy in order for Mukotsu to be able to steal the jewel shards Kagome carries and states she's "all his to enjoy."
When Kagome and Shippo briefly separate from the group to fetch water from a village well, they notice too late that the villagers are dead due to poisonous gases that have encroached upon them. Both collapse, unconscious, and Mukotsu seizes the chance to abduct Kagome. He is briefly confronted by Sango and Miroku, who demand to know who resurrected him and trying to stop him from taking Kagome. Confessing his ignorance of the subject, he easily evades them, having distracted Sango into protecting Miroku from a spray of noxious vapours.
It's shown that Mukotsu has taken her to a hut hidden in the woods, where "no one will disturb them together," as he's surrounded the hut with a barrier of deadly gas. He comments on her beauty and his luck at having her all to himself. In the manga he attempts to rape her, having taken advantage of his poisoned gas paralysing her and leaving her too weak to defend herself. In the anime this is changed to him expressing his desire to have her as a wife and reenacting a bizarre sort of marriage ceremony where he drapes a white cloth over her and moves her paralysed body as if she were a marionette, forcing her to "sing and dance" along with him. Sango and Miroku try to rescue her but are blasted with a stream of poisonous gas and fall under its effects as well. In both scenarios Kagome is able to momentarily regain control of her body and manages to stab him in the throat with hearth tongs, trying to get the jewel shards lodged in there. Rather than damaging him, he becomes enraged at her supposed treachery and resolves to kill her instead.
As Mukotsu strangles Kagome Sesshomaru bursts in and harms Mukotsu severely. He demands to know where Naraku is and is irritated by Mukotsu's ignorance. The frightened Mukotsu attempts to poison him but is shocked to see that Sesshomaru is impervious to his highly toxic brews. He expresses his disbelief in that he'd be so resilient to his specially made poisons, pompously proclaiming himself a master poisoner, only to have Sesshomaru brush his claims off as weakness and promptly cuts him in half with his Tōkijin. Jakotsu witnesses his death and rushes off to tell the Band of Seven of this development and the unexpected interloper.
- He, along with the rest of the Shichinintai, are classified as spectres due to their resurrection by Naraku placing shards of the sacred jewel in different parts of their bodies.
- His name means "misty/foggy skill," alluding to his use of poisonous gases. The last part of his name can also be read as "bone" due to the kanji for skill and bone being the same, further reinforcing his image as an undead antagonist.
- Unlike the rather chivalrous Miroku from the same series, whose lecherous behaviour is often quickly halted by his friends, Mukotsu is a bona fide pervert, openly expressing his lust for Kagome Higurashi. He has referred to her as "my pretty," a "rare beauty," and stated "let's make a good memory before you die, girl" (when he was trying to force himself on her in the manga). The fact that his original intent in the manga was indeed to rape her is further underscored by his comments of his luck at being able to do what he pleased to "such a pretty girl."
- His skill in mixing poisons is brought up several times in the series. In his brief appearance he was able to create massive clouds of fast moving poison, poison that was able to penetrate an opponent's facial orifices, and poison that was able to seep into eyes and skin through clothing. He was also capable of creating gases tailored to attack humans and yokai alike.
- He is noted to have developed a strong resistance to poisons, drinking his own concoctions to test their strength and him casually remarking of his lack of need of a face mask while standing in the middle of a cloud of poison. The cloth he wears draped over his face is merely a decorative effect.
- His hunched physique and elderly appearance place estimates that he was around 60 - 70 or so years old when he was executed, thus making him out to be around 70 - 80 chronologically after he was revived.
- He is stated to be the second weakest member of the Seven Man Band after Kyōkotsu.
- Similar to Jakotsu, he is very misogynistic. Unlike Jakotsu's hate having stemmed from his irritance of women coming between him and the men he's obsessed with, Mukotsu's hatred of women originates from his acknowledgement of his unpopularity with women (which he doesn't realise has nothing to do with his admittedly repulsive looks and everything to do with his creepy attitude and coming on too strong, as Kagome noted) and his treatment of them as objects to lust over. In the manga he didn't even care that Kagome was dying from the effects of his poison as long as he was able to take advantage of her.
- In the anime he's portrayed as being much more insecure and easily insulted about his visage, bringing to light a certain inferiority complex.
- He's incredibly narcissistic and egotistical, taking it to heart that his skill with poisons could be called into question and feeling entitled to the attention of women he wants. He becomes incredibly angered when Sango and Miroku survived his initial onslaught of poison, even more so when Kagome dared to repel his advances, and was positively infuriated when Sesshomaru brushed aside his miasma as if it where nothing and called him weak.
- The tattoos on his face mean "Poison".
- He seemed to be rather close to Jakotsu, appearing with him in the anime's title credits as well as helping him escape from Inuyasha and letting Jakotsu sit next to him and even put his arm around him as well as patting him on the head.
- Despite appearing in all of the corresponding anime season's opening sequence, he only features in two episodes. His stint in the manga is equally brief.
- His garb seems to be a mockery of a pharmacist's uniform, given that he's shown with a mortar and pestle, is dressed in white, and carries his ingredients for his poisons in a basket and jars that correspond with the medical supplies of the time.