Ranmaru possessed a dōjutsu kekkei genkai which, when activated, causes his eyes to glow red in colour. It grants him abilities such as penetrative vision as well as the ability to hinder other dōjutsu such as the Byakugan which his own dōjutsu has been likened to.
This dōjutsu grants the wielder many abilities that include penetrating vision, disruption of other dōjutsu, and unique healing through life-force energy manipulation.
With his kekkei genkai, Ranmaru has the ability to see and hear things from long distances. With this ability, Ranmaru was able penetrate the walls of his shack to view the outside world. Although the range of his kekkei genkai is similar to the range of the Byakugan, it actually has the ability to counter and negate that trait. His abilities also allow him to perform irresistible genjutsu, which can fool even the all-seeing Byakugan. Ranmaru's vision also lets him locate and track others by sensing chakra, picking up chakra from long distances, and noticing changes in an individual's chakra. It is also able to sense how many individuals are present.
Ranmaru's vision has heightened perception and analytical powers like the Sharingan, meaning Ranmaru can comprehend any details he sees, which he uses to predict the opponent's next move in conjunction with Raiga. When first encountering Raiga, Ranmaru was able to read his thoughts and determine what was ailing him. He can also see one's life force, allowing him to determine that Raiga, who had recently fallen in battle, was still alive. In addition to this, Ranmaru is able transfer part of his own life force to completely heal someone who is mostly dead.