Younger Toguro is the younger of the two Toguro brothers, as well as the most powerful member of Team Toguro. He is the main antagonist of the Dark Tournament Saga, aside from Sakyo. He is always calm and collected, as is expressed by the fact that he never removes his trademark sunglasses. He has no plans in life, and spends most of the series serving under Sakyo, one of his most important clients. He's tall and extremely muscular with a slick black hairstyle, but is virtually empty on the inside, having thrown most of his life away in pursuit of what he frequently refers to as "power absolute". His goal in the tournament was to fight Yusuke Urameshi, in large part for the challenge of fighting an opponent against which he wasn't sure that he would win and, later, in order to settle a personal score with him as Genkai's apprentice. In the Japanese version, the Toguro Brothers are commonly referred to as the Brokers of Darkness in their earlier introductions. Younger Toguro is almost never referred to as "Younger Toguro"; Elder Toguro calls him "brother", while the other characters simply refer to him as "Toguro". In the first character popularity poll in Japan, the Toguro Brothers (both under the same candidate) were at 11th place with 141 votes. In the first Shonen Jump poll in America, the Toguro Brothers were in 7th place with 203 votes, which would make them more popular in America than in Japan. In the second Character Popularity Polls in Japan, Younger Toguro was at 10th place with 447 votes.

Younger Toguro is one of the most intricately developed characters in the series, with what is probably among the most explored histories as well. Fifty years before the start of the series, he, his older brother, and Genkai - his implied lover - built a very successful dojo together, supported by many promising young students. However, when a demon named Kairen, who was the favored contestant in the Dark Tournament fifty years ago (the winner of the previous Dark Tournament in the English dub), paid a visit to the dojo during Toguro and Genkai's absence and massacred every one of their students as a "warning" to others participating in the tournament, Toguro went into a state of shock, and disappeared into a state of seclusion for three months. He returned to his team the day before the tournament... however, as Genkai states, he seemed different; detached from reality. The trauma of losing his school to Kairen had warped his mind and turned him into an entirely different person. Both Toguro and Kairen's teams made it to the final round, at which point Toguro managed to kill Kairen, winning the tournament in much the same way Yusuke would later win against him. As their prize, both he and his brother chose to become demons of the highest caliber, a type of demon that was virtually indestructible and would almost never age. Genkai, out of anger, wished never to be involved with or bothered by the tournament ever again.

Some time after this, the two brothers met Karasu and Bui, who they both defeated easily. Instead of killing them off, the Toguros stripped them of their freedom and took them as underlings under the premise that they would one day fight again, later making the claim that there was no motivation stronger than the desire for revenge or freedom. At some point, the Toguro brothers' gang caught Sakyo's eye... however, it is unknown whether this was before or after Karasu and Bui were recruited.

The younger Toguro's main ability is increasing the size of his muscles, assigning a percentage value to each level based on his power as he's so fond of doing. For most enemies he uses anywhere between 1-30% of his power, though he has on rare occasion been shown to fight at levels of up to 80% outside his fight with Yusuke, primarily during his final fight with Genkai. He has never been shown being forced to resort to this level, but rather, he chooses to do so in order to intimidate his opponent and/or to make a point. Only once has he ever been shown fighting at 100% power, which was during his fight with Yusuke Urameshi. While at 100% power, his body became massive - even taller than his normal height and covered with an inhuman composition of muscles to the point of being grotesque - and his skin turned a stone-like gray. He also acquired two cone-like extensions on his shoulders which, if he so chose, had the ability to absorb the souls of the weaker members of the audience, could flick his fingers to create bullets of air or spirit energy (it's never defined which), and by merely flexing his muscles he could shatter a reasonably powered-up Spirit Gun blast. Later in the tournament, it was revealed that he had one level remaining - in the Japanese version it was referred to as 120% power, while in the English dub Toguro noted that what he had previously referred to 100% was really closer to 85%. In his full power form, Toguro looks much like his 100%/85% form except for his even larger shoulder plates and a considerable increase in the size of the extensions on his shoulders and the sides of his face, giving his head a wide, cobra-like appearance. Even though he appears to be the strongest character in the series throughout the Dark Tournament saga and some time after (aside from Yusuke), it is later revealed by Koenma that in his full power form, Toguro only possessed the power of an upper B-class demon. In the English dub, it is stated that both Toguro brothers - elder and younger - are upper B-class demons... however, this claim is not supported by the lack of mention in the manga nor the younger Toguro's effortlessy swatting the elder brother aside prior to his fight with Yusuke, and it is widely assumed that this was just a generalization on Koenma's part.

In the series, the younger Toguro is first introduced in episode 22 with his brother, having been hired by the human crime lord, Gonzo Tarukane, as bodyguards. The Toguro brothers' gang controlled a small army of lower-class demons, placing a large number of them as guards outside Tarukane's stronghold in order to test Yusuke and company and to swindle Tarukane. In truth, both brothers had been hired by Sakyo beforehand, who then instructed them to infiltrate Tarukane's ranks. When the majority of the Black Black Club bet on the Toguro's forces' victory, Sakyo - who had been monitoring Yusuke's progress for some time - twice bet on Yusuke's victory, winning both bets. When it came time for the final bet, Sakyo once again bet on Yusuke's victory, offering an enormous sum of money that would leave Tarukane penniless should he win the bet. When the two brothers faced the rescuers, under Sakyo's unspoken command, the brothers faked their own death in order to ruin Tarukane and make Sakyo's fortune. When everyone else left, Sakyo ordered Toguro to kill Tarukane, who was no longer of use to him.

Shortly after, Toguro approached Yusuke on the street, telling him that he was one of that year's "guests" in the Dark Tournament. If Yusuke and his team didn't make it to the final round, or if they refused to enter, Toguro threatened to kill everyone he knew and cared for. Throughout the Dark Tournament, he made several minor appearances commenting on matches and single-handedly winning all but one match for his own team - the semifinal match being one that he was absent for. He also was ordered by Sakyo to kill several people, including the tournament committee and the owner of Team Masho. Just after the semifinals, Toguro fought off against his old friend, Genkai, and managed to kill her at 80% of his power, much to Yusuke's torment.

Younger Toguro's role came at its height when he fought a very lengthy battle against Yusuke Urameshi. Prior to the fight, the elder Toguro managed to reform from his fight with Kuwabara, and after a brief and somewhat insulting comment about his brother, offered to assist him in his fight with Urameshi. The younger Toguro, however, refused his offer, kicking him into the air. When the elder brother retaliated, he effortlessly sent his elder brother flying out of the arena with a powerful uppercut, presuming him dead, then began his fight with Yusuke. For a while, each of them continued to release handicaps and increase their strength until Toguro reached 100% and killed several audience members with the extensions on his shoulders. Realizing many would die if Toguro wasn't defeated at any cost, Genkai possessed Puu and told Toguro to kill Kuwabara so that Yusuke's full strength could be reached through the pain of loss. After supposedly driving his hand through Kuwabara's heart (while in truth sparing his life, unbeknownst to Yusuke), Yusuke's power was released and he began to gain the advantage... so much so that Toguro was forced to go beyond his normal limits and enter his full power form. Both decided to end the fight one way or the other by releasing all their power at once, with Yusuke expending all of his spirit energy forming an enormous Spirit Gun blast and Toguro expending all of his energy in order to block it. While Toguro was unaffected by the attack itself, he spent too much of his energy in stopping it barehanded, after which point, he thanked Yusuke for allowing him to fight at full power. His demon body then shattered, and he died where he stood. In the afterlife, Koenma offered Toguro a light punishment because of his noble past as a human martial artist, and his regret for the way he had lived his life. Toguro, however, refused, and asked to be sent to the deepest level of hell - Limbo in the English version - where he would suffer beyond imagination for 10,000 cycles of 10,000 years each. On his way, he stopped briefly to speak with Genkai, who had known that he would go there and attempted to persuade him not to do so, telling him that he had suffered enough. Toguro asked Genkai to watch over Yusuke to ensure that he doesn't go down the same path that he did, and apologized to her for "being so much trouble" in life. Before walking through the gates of hell, he expressed his regret to her, telling her that "it would have been a beautiful life."