Chowa Seal

The Chowa Seal is a unique seal that takes the form of a cross-hair on the user's chest. The seal is not widely understood or known, Machiko seems to imply that this ability is a genetically warped version of a Kama Seal, and may have come from the genetics of Kaguya Otsutsuki.

Abilities
Initially, Strike Nebimura subconsciously activated the ability during times of great strain and stress. When this occurred, it awakened in it's 'Form 1' mode, which allowed Strike to tap into the "conscious abilities of those around him". This initially manifested as Strike having the Sainos of others. When in the Form 1 mode, the Seal extended up his face and over his left eye in a straight line, with a distinct crimson colour. It also turned his left eye red.

After his near death during the Konoha Civil War, Strike subsequently activated Form 2 of the Seal, after communing with the spirit of Masako Uchiha. In this form, Strike is able to utilise the Chakra and abilities of those around him. In this instance, Strike was so powerful that he could heal fatal wounds, bend the air around him with his dense chakra, and crush the terrain around him when taking footsteps. All of this stems from him having access to the Chakra of others, including the Nine-Tails, who was summoned by the Uchiha Clan at the time. In Form 2, the seal extended over both left and right eyes in a straight line. The drawback to this Form is that it is short lasting, Masako Uchiha compared this to a 'quick burning candle', which he elaborated as 'powerful and bright, but short burning'. The repercussions of using Form 2 was that Strike was left unconscious for 3 days and completely drained of his own chakra.

Form 3 and 'Form 4'
It has been theorised by Strike and Masako that two stronger versions of the Seal exist, but Strike has yet to obtain this. Masako believes that he has a fair understanding of what Form 3 could be, which he describes as a 'more powerful and longer lasting Form 2'. Which, if true, would give Strike power levels exceeding that of the Five Kage combined. Albeit with a much more fatal drawback than Form 2.

Form 4 is something that is purely theoretical according to Strike, and is the only part of the Seal that Masako himself really does not comprehend. Strike believes there to be a form beyond Form 3 but Masako Uchiha disputes this, stating that nothing could exceed Form 3.

Origins and Users
It is stated by Machiko that the Chowa Seal comes directly from the bloodline of Kaguya Otsutsuki. Machiko considers the Chowa seal, 'a deformed version of the Kama Seal' which is obtained by killing a member of the Otsutsuki Clan. Machiko believes that Masako Uchiha may have inherited the recessent gene necessary to create a Chowa Seal (due to the Uchiha Clan being directly related to Kaguya) - and believes he passed it to Strike when he used his Mangekyo ability to transfer a portion of his spirit on him, which subsequently awakened the Seal within Strike.

Strike Nebimura
Strike Nebimura is the only known active user of the Chowa Seal, having received it through the Mangekyo Sharingan of Masako Uchiha on his deathbed.

Masako Uchiha
Masako Uchiha, while not ever actively possessing the Seal, did inherit it through his genetic connection to Kaguya Otsutsuki, and subsequently he passed it on to Strike Nebimura on his deathbed, who actively awakened it.

Kaguya Otsutsuki
While it is not actually known if he actively possessed the Seal or not, it is known that the seal derives from her genetics.