Reisei

Reisei (霊性, Divine Nature) is a partially dōjutsu kekkei genkai that is was originally thought to be unique to Hitsuyō no Mikoto before it appeared several years later in her son Nōsei. While the dōjutsu accessed by Reisei is not one of the three great dōjutsu, it is believed to mark an evolutionary intermediate between the Rinnegan and the Sharingan.

Abilities
Similar to the Sharingan the dōjutsu portion of Reisei is not available at birth. Instead its activation is triggered by an emotional or stressful situation. Even after this initial activation the user may not fully master its activation and deactivation for some time, as seen with Nōsei. Until control over this dōjutsu is fully master it may activate and deactivate at random, which lead Nōsei to constantly wear sunglasses in public for fear of being targeted for having a kekkei genkai. This random activation and deactivation seems to be accompanied by the onset of intense migraines which will plague the user until the dōjutsu is mastered. While intense training appears to increase the speed at which this kekkei genkai is mastered, time seems to be the primary factor.

Despite the harsh drawbacks that are associated with the mastering phase of Reisei's dōjutsu, the abilities offered in return are quite useful. When activated the dōjutsu, sometimes referred to as the Seizongan (生存眼, "Existence Eye"), allows access to two abilities which appear to mark its relation to the Sharingan. The first of these is the ability to visualize the flow of chakra, which is usually invisible to the unaided eye. The second is incredible clarity of vision which allows the user incredible reaction time and accuracy. Because of this incredible perception the user is able to visually track of incredibly quick moving objects, and recognize subtle inconsistencies while under a genjutsu. While the Seizongan allows these two abilities that reflect its relation to the Sharingan, it cannot cast genjutsu, nor can it copy the techniques of others.

While the distinctly dōjutsu abilities reflect Reisei's relation to the Sharingan, this kekkei genkai abilities are not limited to the eyes. While wielders of the Rinnegan have access to every single basic elemental nature, with the addition of the Yin-Yang Release and its components, those accessing the power of Reisei reflect this ancestral power by gaining access to just the Yin Release. Like all users of the Yin Release

Similar to the dōjutsu power, Reisei doesn't grant a user the power of Yin at the point of birth. Unlike the dōjutsu though this skill manifests itself only if the user attempts to train in it. Furthermore, it is suspected that some of the people who have claimed to have the Yin Release kekkei genkai, are instead Reisei wielders who never unlocked the dōjutsu portion of their bloodline. Likewise it is not impossible for a user of Seizongan to never learn of their Yin Release potential, as the two sets of abilities are independent of each other and represent a highly recessive genetic link between the Rinnegan and the Sharingan.