Kāma

Kāma is a seal bestowed by members of the Ōtsutsuki clan that takes the form of a four-point black diamond on the recipient's body, marking them as a for the Ōtsutsuki's will, allowing them to eventually take over the vessel's body and. Over time the Kāma, ultimately causing the vessel to awaken as a perfect Ōtsutsuki. As Kara solely holds all intel on the seal, the phenomena largely remains a mystery.

Known users

 * Jigen bears the mark on his chin as the current vessel for Isshiki Ōtsutsuki. When activated it spreads across his face and body in nearly symmetrical sunburst patterns. Progressing further, he sprouts a long horn identical to Isshiki's.
 * Kawaki received the mark on his left palm through scientific experiments conducted by Jigen. When activated it spreads across the left side of his body forming a pattern that almost perfectly mirrors Boruto's, extending up to his left eye, and then glows red. Progressing further, he sprouts a short horn resembling Isshiki's.
 * Boruto Uzumaki received the mark on his right palm from Momoshiki Ōtsutsuki after dealing a fatal blow to him. When activated it spreads across the right side of his body forming angular and curving geometric patterns, extending up to his right eye, and then glows blue. Progressing further, he sprouts a horn similar to Momoshiki's and his right eye turns into a Byakugan.

Abilities
When activated, Kāma significantly enhances the user's physical abilities and jutsu's power. The Kāma can absorb, retain, and release an enemy's attacks like ninjutsu, and unleash large-scale explosions. Boruto's and Kawaki's Kāma exhibit when in close proximity. When their Kāma resonate, it apparently enables them to release anything that either of them had previously absorbed. This resonance also seems to be independent from the origins of the involving Kāma, as Kawaki got his from Jigen, while Boruto got his from Momoshiki. Jigen and Amado theorised that it was this resonance that allowed both Kawaki's and Boruto's Kāma to mature more rapidly than expected.

Kawaki could activate it at will by the time he first met Boruto and three years later, Boruto was able to activate the seal at will as well, while Jigen was fully capable of activating it any time he desires. Boruto's resonated Kāma could also be forcefully activated when Kawaki activates his own nearby.

Kāma can also be used as a medium for Space-Time Ninjutsu, opening rifts to any location including foreign dimensions at will. This ability seems to be rather advanced as only Jigen was able to use it by himself, Boruto and Kawaki's needing to cooperate to use it instead.

Through the aid of science, Jigen can use his Kāma to transfer it to other individuals, albeit with a low rate of success, as of fifteen known test subjects, thirteen are confirmed to have died, with Kawaki the only known successful recipient. Jigen has also shown the ability to absorb chakra from creatures that are similar to tailed beasts and force Kawaki's Kāma to synchronise with his for him to open a portal to his location.

As the Kāma makes anyone who receives it a vessel for Ōtsutsuki chakra, the Ōtsutsuki who gave them the mark can be manifested to possess the body of the vessel, causing their signature horns to protrude from different sides of the vessel's temple. This is highly difficult to achieve, as Kawaki only recently activated it due to his advancement subconsciously, which made Jigen acknowledge Kawaki has greatly advanced the seal, and Boruto only manifested Momoshiki after he was knocked out by Boro, and extended use of it can greatly wear down the vessel's body: Momoshiki had to absorb Naruto's chakra to continue fighting until he killed Boro in Boruto's body and he soon collapsed. Additionally imperfect vessels can break down from the sheer power the Ōtsutsuki was using, as though Jigen could activate it willingly, he was unable to handle Isshiki's full powers for long and began breaking down after a while. However, in the case of fitting individuals like Kawaki and Boruto, the seal will apparently transform the vessel into their respective Ōtsutsuki clan member.

Drawbacks
Using Kāma in battle could prove taxing for less skilled users, even more so when they are already weakened, as Kawaki quickly collapsed after using it against Garō as he was already injured from defeating Kara's robots while Boruto was left so badly weakened after using it for the first time that he collapsed and had to be helped to return to Konoha. Additionally, activating it seems to cause a not sufficiently experienced user some pain, as Boruto expressed pain whenever he activates Kāma. Jigen doesn't seem to suffer these weaknesses as he is much more capable at using them than either Boruto or Kawaki, as he never showed any reaction when activating Kāma and using it in his prolonged battle with Naruto and Sasuke had no effect on him. However, one known weakness of the seal that even Jigen seems to suffer from is that incomplete vessels could breakdown from channelling Kāma's full power, as after overpowering Naruto and Sasuke, the blackened section of his body cracked and he even cried soon afterwards and was forced to retreat back to be treated by Amado.

Kāma cannot absorb non-chakra based physical matter, such as viruses, thus becoming a vulnerability towards such attacks and weapons.

Trivia

 * Although the kanji itself would normally be translated as, the furigana indicate the reading . "Kāma" means "wish", "desire", or "longing" in Hindu literature. In Japanese it is also an uncommon way to write "karma".
 * Sarada Uchiha has theorised, due to their similar appearance, that the Strength of a Hundred Seal may be related to it. However, Shojoji says it's more similar to Orochimaru's Juinjutsu.