With the manga by Boruto: Naruto the next generations We were left behind at a very important point in the plot where the clash with Isshiki Otsutsuki dominates. Unpredictably, the alien had found Boruto as an enemy, weak but apparently impossible to kill for reasons unknown.
Boruto: Naruto Next Generations 51 shed light on this mystery and also revealed other characteristics of the Otsutsuki and some of their methods of attacking a planet. In fact, the aliens always travel to a world in pairs, as the tentails cannot put down roots without eating nutrients of a certain type. The The nutrient in question is just an otsutsuki: One of the two members of the couple, usually the lower-ranking one, must sacrifice itself and become food for the animal in order for the tree and fruit to bloom. Originally, Kaguya was the victim.
What is produced then becomes nourishment for the higher ranked otsutsuki, while the lower ranked one will return thanks to the previous use of karma. Therefore Boruto suddenly became important to Isshiki. According to the main plan, Isshiki had to do everything himself and for this he had to plant karma in Kawaki, then feed the ten-tails with Jigen's body and finally return to the young man's body, then devour the fruits of the tree and more will become strong.
A precise plan, but made easier by the presence of Boruto. Isshiki can actually use him as a victimwithout having to feed the ten tails and do everything yourself. The protagonist will then be alive for some time, but with a sword over his head that could fall on him at any moment.