In Boruto: Naruto Next Generations, Uchiha Shin's Mangekyo Dojutsu was utterly pathetic: it merely allowed him to manipulate weapons, and he first had to touch them to leave a mark.
The abilities of the Mangekyō Sharingan originated from the deepest, most extreme desires within an Uchiha's heart.
As one of Orochimaru's test subjects, Uchiha Shin had been positioned as a tool, a weapon.
That positioning had severely affected Uchiha Shin's self-perception.
After Uchiha Shin betrayed Orochimaru and sought to rebuild the Akatsuki Organization, what he needed was also a large number of subordinates he could use as weapons.
Under those circumstances, it was hardly surprising that his awakened Mangekyo Dojutsu allowed him to manipulate weapons.
But things were different now.
An did not see Shin as some weapon, but as one of his own clansmen.
Influenced by An, what Shin desired most was not to become An's weapon, nor to control more weapons in An's service. Instead, he wanted to diligently study cloning in order to revive the Uchiha Clan and shoulder the responsibility of its restoration.
Under those expectations, the Mangekyo Dojutsu Shin awakened was naturally composed of abilities related to that goal.
The Dojutsu in Shin's left eye was called "Principle Tracing and Reconstruction," while the one in his right eye was called "Causal Analysis of Myriad Phenomena."
"Principle Tracing and Reconstruction" used Yin Release Chakra as a probe. When he gazed upon a Ninja Tool, Forbidden Technique, or living body, he could reverse-engineer its underlying logic, clearly investigate its construction principles, understand its core sequences, and even reconstruct its fusion order and proportions.
"Causal Analysis of Myriad Phenomena," on the other hand, skipped the process and went straight to the result. Once activated, it could construct a Ninjutsu Formula experimental sandbox within the eye, repeatedly simulate experimental