Gengo

was the leader of the Land of Silence, until his imprisonment in the hands of Anbu.

Background
Gengo, alongside other fellow shinobi from Kirigakure at the time, allied with Zabuza Momochi in rebellion against the Fourth Mizukage, Yagura, and his destructive methods of ruling over the village. However, due to a traitor in their group, Zabuza and the rest of his fellow followers, including Gengo, were forced to flee the village forever. After the event, Zabuza and most of his other followers began collecting capital as mercenaries, never letting go of their dream to go back to their motherland. However, then Zabuza began accepting work from corrupt people, Gengo, alongside many others, left and became disillusioned about such goals.

Upon leaving the group, Gengo made his way to the Land of Silence and took over the nation. During his time ruling it, he developed a genjutsu-inducing speech technique to further his goal of controlling others for his bidding.

During the Fourth Shinobi World War, Gengo grabbed the opportunity to put his new abilities and plan to action, abducting young men from war and placing them under his control to form Enlightened Ones. This continued for two years after the war and he slowly built up his power, having brainwashed minions to take smaller missions from Shinobi Union in hopes of building a vast amount of capital for his goals.

Genjutsu
Gengo is a very powerful genjutsu user, having the ability to create mind-controlling illusions without the need of hand seals or eye-contact, being nearly undetectable and impossible to be blocked or dispelled, even when figured out by the victim. Gengo created a genjutsu-inducing speech technique that allowed him to control targets using his voice alone, leaving victims in a brainwashed state and making them worship the caster. After losing his ability to speak, however, Gengo became incapable of using such genjutsu again.

Kenjutsu
Growing up in Kirigakure and being a follower of Zabuza, a member of the Seven Ninja Swordsmen of the Mist, Gengo trained himself in kenjutsu, like many other younger shinobi from his hometown.

Shikamaru Hiden: A Cloud Drifting in Silent Darkness
As Gengo's Enlightened Ones began to grow, he began to attract attention to himself from the rest of the world, particularly the Shinobi Union as they began to realise many of their young men began to disappear while investigating his nation for stealing their potential jobs. His latest brainwashed recruits, which included rising star in Konoha's Anbu Sai, prompted Konoha to order his capture or assassination.

During one of Gengo's many speeches meant to keep everyone in Curtain Village, Gengo captured Konoha shinobi meant to assassinate him — Rō, Soku, and Shikamaru Nara, who (while under the effect of his genjutsu) he had quickly detained. Upon realising he had captured Shikamaru, Gengo was ecstatic and quickly started attempting to sway the young genius into becoming his right hand man. Despite almost succeeding in placing Shikamaru in the brainwashing genjutsu, Temari and a battalion of Suna and Konoha shinobi stormed Gengo's throne room and interrupted Gengo's genjutsu. Much to his horror, Shikamaru quickly was able to understand Gengo's abilities and Temari began using her tessen to create loud noises to drown out Gengo's chakra infused voice.

Realising he had been defeated, Gengo fled his Enlightened Ones as Shikamaru gave chase. In a darkened room, Gengo tried to use kenjutsu to kill Shikamaru but due to Shikamaru's master plan and the arrival of Shikamaru's ANBU partners and the rest of Team Asuma, Gengo was detained. Hinoko then used her Chakra Needle to disable Gengo's ability to speak ever again, demoralising Gengo as he was taken away to the Shinobi Union's headquarters in the Land of Iron.