Youji Aburame

Youji was raised by an abusive father who was jealous of Youji's natural talent. When Youji accidentally spilled juice on his father on his fifth birthday, his father slit his throat to punish him. Youji retaliated by killing his father. Orphaned, Youji was soon recruited into Root, a faction of the Anbu led by Danzou Shimura. Because he'd lost the ability to speak when his father attacked him, Danzou taught him how to use the insects that inhabited his body to produce words. Though effective, it made his voice sound weird and tired him out, for which reason he preferred to remain silent. When Itachi Uchiha joined the Academy, Youji was assigned to pose as a student and observe Itachi, passing along reports about Itachi to Danzou. A year after Itachi graduated from the Academy, Youji was assigned to Itachi's Team 2 so that he could continue to watch him. The two never spoke, and Itachi left the team after only a few months. A few years later, when Itachi joined the Anbu's Team Ro, Youji - using the codename Sugaru - was also added to the team. Officially he was just another member, but Danzou informed Itachi that Sugaru's sole responsibility was to keep Itachi safe from harm. As the Uchiha clan began moving towards a coup, Sugaru continued to watch Itachi both during and after Team Ro's missions, the latter in secret. In doing so he learned of Itachi and Shisui Uchiha's plans to try and stop the coup by using Kotoamatsukami on Fugaku Uchiha. After reporting this to Danzou, Sugaru used his insects' poison to subdue Shisui, enabling Danzou to take Shisui's Mangekyō Sharingan for himself. Shisui escaped before his second Mangekyou could be taken, but the insects' poison couldn't be removed and he would die anyway; the poison would then break down so it wouldn't show up during an autopsy. Sugaru continued to watch Itachi on Danzou's instructions. When Itachi left the village following the Uchiha Clan Downfall, he called out Sugaru, aware that he would be followed wherever he went. Sugaru didn't believe Itachi could do anything to stop him, but was quickly proven wrong: Itachi used Tsukuyomi on the insects inhabiting Sugaru's body, preventing him from moving. He then used Amaterasu on Sugaru, burning him and each of his insects until only ashes remained. Sugaru, via his insects, cried out in agony as he died, finally avenging Shisui.