Renkotsu

was a killer who was also a member of the Shichinintai. An expert military engineer, he created explosives and incendiary devices, including a type of flaming oil that he could spew from his mouth. He also reconstructed Ginkotsu into a living artillery weapon resembling a modern tank. He was also a gifted strategist and had some skill at hand to hand combat, although the only members of the group he surpassed in fighting skills were Mukotsu and Kyōkotsu. One of the most dangerous members of the Band of Seven, Renkotsu was second in command after Bankotsu.

During the story
Renkotsu first appeared in the anime taking over a Buddhist temple; however, his scene is omitted from the manga. He then took Inuyasha and his poisoned friends in after his battle with Ginkotsu and gained their trust. Later, after Ginkotsu attacked Inuyasha at the temple, Renkotsu set the temple with Inuyasha's friends in it on fire, but not before stealing Kagome's Shikon Jewel Shards. He was spared by Inuyasha, and he and Ginkotsu regrouped with the Band of Seven.

He reworked Ginkotsu into a tank, and then along with Jakotsu and Ginkotsu, collected Suikotsu. When reunited with Bankotsu, he was forced to give up the shards he stole from Kagome. Bankotsu promptly threatened Renkotsu with death if he kept more shards for himself. Renkotsu appeared later with Ginkotsu, fighting Kōga. They gained the upper hand at first, but Kōga caused Renkotsu to fall from Ginkotsu's back after critically injuring him. Ginkotsu, angered, unleashed all of his artillery upon Kōga. Kōga defeated him, but Ginkotsu self-destructs and used his Shikon shard to protect Renkotsu (in the manga, Kōga stuffed Renkotsu's armor into Ginkotsu's cannon, causing it to explode). Renkotsu used Ginkotsu's shard to heal his wound, despite knowing Bankotsu would kill him for doing so; his justification for this was that he would do anything to survive. Because Bankotsu's orders continued to send various members of the Band of Seven to their eventual deaths while returning their jewel shards to Bankotsu, Renkotsu used this to justify his plan to betray Bankotsu.

He then attacked again by trapping Inuyasha, Kagome, Kōga, and Kōga's followers into a cave. He defeated Inuyasha, and prepared to cut out Kōga's jewel shards, but then was handily defeated by Inuyasha's timely appearance. Later, after Inuyasha entered the barrier surrounding the Band of Seven's fortress and became human, Renkotsu chased him and toyed with the helpless Inuyasha. Inuyasha slipped through a crevice just as Jakotsu arrived; knowing Jakotsu had an obsession for killing Inuyasha, Renkotsu sent him after the half-demon, hoping the two would destroy each other. His reason for this wass that Jakotsu was too loyal to Bankotsu to join his betrayal, and he needed Jakotsu's shard. Renkotsu observed the battle and removed Jakotsu's jewel shard after he was defeated by Inuyasha, apologizing to Jakotsu. With three jewel shards, he challenged Bankotsu, but dies after Bankotsu, deeming him a traitor, cut all of the jewel shards out of Renkotsu's body.

Renkotsu's death happened slightly differently in the anime. When he found Bankotsu, Bankotsu had already been told by the Saimyōshō of his betrayal of Jakotsu. Renkotsu thought that if he could keep Bankotsu from using Banryū, despite Bankotsu having one more shard, they should be evenly matched, but then Bankotsu reached up and yanked out Renkotsu's stolen shards, revealing his treachery. Infuriated, Renkotsu berated Bankotsu for sending the Band to their deaths once again, and stated the only reason Bankotsu could overpower him was because of their Shikon Jewel shards. Insulted, Bankotsu returned the shards to Renkotsu and challenged him to prove it by fighting him, laying Banryu aside. Suddenly, unnerved despite having the shards, Renkotsu hesitated, and Bankotsu attacked. It was immediately clear that Renkotsu's combat skills were completely inferior to Bankotsu's; panicking, he unleashed his artillery and his flame gourd, but it barely held Bankotsu back. Bankotsu threw Jakotsu's hairpin and hit Renkotsu in the chest, paralyzing him and knocking out one of the jewel shards. Angrily, Renkotsu screamed at him, "How is what I've done any different from what you've done?!" Bankotsu ripped out his other shards in response; as Renkotsu crumbled into a skeleton, he answered, "The difference is... I would never betray my friends."

Physical description
Renkotsu was bald, which was thought to be because it was said he was once a monk/priest (in support of this theory, he was able to write). He had tattoos upon his face which stood for Deception. He usually wore armor and a bandana. His original armor consisted of a blue undershirt with a reddish-orange armor, but after his battle with Kōga, in which much of his armor was torn off, Renkotsu adopted a new outfit with a black undershirt and orange armor with a flame-like design.

Powers & Abilities
Although not a formidable fighter like Bankotsu, Jakotsu or Suikotsu, Renkotsu made up for his lack of combat skills with his advance weaponry. He was a master of chemistry, explosives, metallurgy & mechanics. He used a variety of fire-based weapons, including "steel" strings that light on fire, cannons, and dynamite. He could also breathe fire by drinking a special oil and spitting it from his mouth (no explanation was given as to how the oil was lit, as it came from his mouth as fire). He also had a wooden wheelbarrow that he used to carry his artillery after Ginkotsu's death. It was his invention and engineering skills that allow him to rebuild Ginkotsu after his original body was damaged beyond repair.

Arguably the most cunning and intelligent member of the Band, Renkotsu was skilled in stealth and strategy; he was usually in command if Bankotsu was engaged in other matters, and unlike the others he rightly mistrusted Naraku (although the two never met face-to-face). He was also the only member of the Band besides Bankotsu who knew how to write. After Ginkotsu's demise, Renkotsu relied upon himself to take arms against his enemies, carrying a load of them in a cart. Ultimately, Renkotsu's cunning was his downfall, as it caused him to betray Bankotsu for his own survival. Bankotsu admitted that Renkotsu might have been able to usurp him if he hadn't hesitated so often to figure out the details of his plan, remarking, "For being the smart one, you sure can be stupid."

Weapons

 * Fire Gourd: Renkotsu had a gourd attached to his wrist which had an extremely flammable liquid inside of it, which he drank, then spits out as flames. This was his most commonly used and simplest weapon.
 * Fire Wire: Renkotsu had wires which he wielded with his fingers. He could set them on fire instantaneously and use them to bind his opponents.
 * Fire Net: With his fingers interlaced, Renkotsu could make the wires form a net to keep the target from escaping by leaping/flying.
 * Fire Whip: Renkotsu could use a single Fire Wire as a whip.
 * River of Flames: Not really so much of a technique as a strategy, the idea of this strategy was to catch Kagome and Kōga at the foot of the mountain of the spirits. Renkotsu threw oil on the river (after making a dam from rocks dislodges by explosives) and then set fire to it, forming a layer of fire on the river.  Renkotsu's backpack contained canisters of oil and lighting devices for this purpose.
 * Flamethrower: A pump-like device that launched a whirlwind of fire from it by pushing a pump in the back.
 * Bazooka/Cannon: A weapon of Renkotsu's that fired explosive rounds by pressing switch/button.
 * Gatling Gun: Another of Renkotsu's weapons that could fire light explosive rounds in quick succession.
 * Explosives: Renkotsu used various types of explosives such as bombs, dynamite, etc. which were carried in his backpack.
 * Lighter: Renkotsu also carried a small lighter to act as a flint for his incendiaries.
 * Knife: Renkotsu is, besides Mukotsu, the only member of the Band of Seven who never displayed hand-to-hand combat skills. However, he was shown to carry a long knife in his belt, which he intended to use to remove Kōga's shards. This, his agility, and the fact that he killed all the monks in the temple without his firepower, suggests he had at least basic knowledge of hand-to-hand combat.
 * Sensor: He used a small sensor to put certain people to sleep. It worked at a rather fast speed, knocking out both Kagome & Shippō in seconds.

Trivia

 * The tattoos on his face mean Deception, referring to him often using trickery to get what he wants.
 * Renkotsu's Theme-Music from the InuYasha Official Soundtrack, Vol. 3 is entitled "The Evil Renkotsu".