Kekkei Sonae

Kekkei Sonae (血継供え, "Bloodline Offering"; literally meaning "an offering of blood inheritance") is the act of Seireitou Hyūga granting an individual a unique Kekkei Genkai through a special ritual in which said individual consumes a small portion of Seireitou's blood. Doing so allows Seireitou to impart some small piece of his unique chakra into that individual infused with his own will in order to grant them a new ability; though the actual mechanics as to how this is possible remain a mystery. It is unknown whether or not Seireitou can grant an individual the Kekkei Tōta or Kekkei Mōra.

Upon becoming Hokage, Seireitou saw it fit to put all the jōnin in Konohagakure through this ritual in order to further empower the strongest shinobi in his village. Certain examples include:
 * Granting Might Guy the Steel Release, to further strengthen his Taijutsu.
 * Granting Kakashi Hatake the Storm Release, in order to empower his Raikiri.

Trivia

 * This ritual is derived from a similar ritual used by Yhwach, to impart a fragment of his soul onto a Quincy to grant them a unique power, from the manga series Bleach.