From the moment karma was first introduced in the Boruto manga, the Hidden Leaf Village started considering the protagonist a threat due to the possibility of him losing control of his body to Momoshiki. The concern became much worse when Momoshiki first took over Boruto's body. Since then, the protagonist has had an internal struggle with the Otsutsuki over control of his body.
With that in mind, the characters did try to get rid of the karma or slow down the Otsutsukification process. Unfortunately, all attempts were deemed useless after the Otsutsuki merged his data with his hosts', turning the protagonist into an Otsutsuki. Now, there is realistically no method to separate the host from the Otsutsuki. That's when one Boruto fan came up with a reasonable theory.
Disclaimer: This article may contain spoilers from the Boruto manga.
Uzumaki clan's Dead Demon Consuming Seal could help Boruto separate himself from Momoshiki
One Boruto fan on X, @Marcelpi3, theorized that the Uzumaki clan's Dead Demon Consuming Seal could be used to kill Momoshiki Otsutsuki. This is because the sealing technique allows one to call upon the power of a demon to extract a soul from one's target.
Upon extracting the soul, the user could potentially separate Boruto's soul from Momoshiki's soul and specifically target the Otsutsuki's soul and seal it away. While one may think that it would be impossible just to target Momoshiki's soul, the Naruto anime did give hints at the possibility of the same.
The jutsu has been used twice in the anime: once by Third Hokage Hiruzen Sarutobi against Orochimaru and another time by Fourth Hokage Minato Namikaze.
When Hiruzen Sarutobi used it, his physical strength at the time made him incapable of sealing Orochimaru's entire soul. Thus, Hiruzen was forced to target a portion of Orochimaru, i.e., his hands to seal away. This incident saw Orochimaru's hands get sealed away, due to which the Sannin's arms got paralyzed.
Meanwhile, when Minato Namikaze activated the sealing technique, he used it to separate Kurama's yin and yang. Right after, he sealed the yang portion within Naruto and the yin portion within himself.
With this, it can be confirmed that the user of the Dead Demon Consuming Seal can target what they want to specifically seal away. Unless both Boruto and Momoshiki's souls were merged with each other, the possibility of specifically targeting and sealing away Momoshiki's soul remained high.
The only issue with this theory is that the sealing technique drains the chakra and life force of its user drastically. This was observed in both cases when the jutsu was used in the anime. Both Minato and Hiruzen died moments after they used the technique.
Hence, if the protagonist wished to separate himself from Momoshiki Otsutsuki, he would have to be ready to sacrifice someone. More importantly, someone should be prepared to sacrifice themselves to help him. Another problem with the jutsu is that only a handful of people know how to use it.
Fortunately, one of them was Orochimaru, who could use the jutsu and also possibly save himself by switching bodies. Therefore, if the protagonist wishes to seek someone's help with the technique, he need not look any further than the Sannin.
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