Pīku

Pīku (ピーク,Peak) is a Yin-release Kekkai Genkai seal found on members of the Honoka Clan.

Origins
The piku is a unique ability granted to the Honoka clan due to their inherent ability to control and master Yin release more proficiently than any other clan.

The piku is achieved through spiritual enlightenment. This form of enlightenment is defined as inner peace or inner ambition and can be achieved through meditation, unified emotion, or an unshakeable ambition to complete a certain task.

When Kashikoi unlocked the piku he inadvertently obtained the purest form of the ability. Due to years of battle, the clan was forced to procreate with other members of the same bloodline.

This meant the Piku Kashikoi obtained was only obtainable through that period's environment and living conditions.

When Kashikoi married outside of the clan and had two kids the pikus ability was instantly diluted.

This created two separate kekkai genkai.

Piku Types
Pikujeido/ Green piku the pikujeido is the greenish variant of the pikuaka. It is granted to those who are descendants of the younger son and gives them the ability to sense spiritual energy, your literal spirit, through yin release, and if the ability is trained it can make an individual so in tune with heir own spirit that through advanced meditation they can project their spirit outside their body.

Pikuaka/Red piku is the original piku while much is unknown about all the seals abilities it is capable of producing spiritual weapons, mastering yin sensory, creating advanced genjutsu, and even seeing shinigami without the use of sealing techniques.

Pikuburu- A blue variant of the piku is one granted to the descendants of the older son. It grants the user the ability to create spiritual weapons, regenerate non-critical wounds, and create truth-seeking balls comprised of yin release which are capable of defending against genjutsu and taijutsu.