When does someone receive the Kāma seal?

Question

Is Kāma in Boruto granted to someone by an Ōtsutsuki's own will? Or will someone who killed an Ōtsutsuki be granted automatically?

For the case of Jigen and Kawaki, it is mentioned in some sources that they are considered as a "vessel". While for Boruto it's because of killing Momoshiki Ōtsutsuki.

Does it mean that Momoshiki Ōtsutsuki gave his power to Boruto by his own will? When did it happen that Momoshiki agreed to give Boruto his power? Or it was granted automatically after Momoshiki was defeated?

If it is because of the latter, in episode 135 of Boruto, does it mean Boruto or Naruto will inherit Urashiki's chakra too since they were able to defeat him?

P.S. I'm not reading the manga.

Answer 1

Kāma attribution is not automatic, but a conscious act from an Otsutsuki.

As of now, including the Boruto manga, we have been able to observe 3 different Kāmas which I will try to explain without spoiling the scenario. Be aware, however, that for the 3rd Kāma, I will delve into spoiler territory as I will need to talk about a character which has not been shown yet in the Boruto anime.

1. Boruto : Momoshiki implanted the Kāma on his hand by projecting his soul and chakra, and willingly marking him as a Kāma vessel.
2. Kawaki : A teenager who has been extensively experimented upon by Jigen and his cronies. Kawaki received a copy of Jigen's very own Kāma through scientific means and chakra transfer, which is a completely intentional transfer.
   3. Jigen :

      3. Jigen : A man of unknown origins. His Kāma (identical to Kawaki's) stems from Isshiki Otsutsuki, Kaguya Otsutsuki's consort. He is a perfect vessel, meaning his personality has now been definitely erased by Isshiki and solely houses the Otsutsuki. Isshiki seeks Kawaki's body because he also is a perfect vessel.

The word "vessel" is crucial, because the main purpose of the Kāma is to create a literal vessel for the Otsutsuki soul which created the Kāma (as confirmed by Jigen himself). It is unconfirmed for now, but Momoshiki could try to take-over Boruto's body later on. We know that Otsutsukis can reincarnate after death, or at the very least transmit their power to individuals they are related to : Naruto and Sasuke were the "transmigrants" of Ashura and Indra, semi-reincarnations influenced by their ancestors. The Kāma bonded Boruto to Momoshiki in death like Ashura and Indra are linked to Naruto and Sasuke by blood.

Tl;dr Kāmas are granted by Otsutsukis who need to hijack a new body