In Jujutsu Kaisen, the Shibuya incident reaches a pivotal point in the battle between Sukuna and Mahoraga, where Sukuna's use of the curse reversal technique becomes the highlight.
This arc reveals a fascinating aspect of Sukuna's personality: his ability to heal others with this technique, despite his reputation for being selfish and cruel.
The Reverse Cursed Technique projection is shown to be a powerful tool capable of destroying Curses with a single blow, which Sukuna used to save Megumi Fushiguro from Mahoraga. This situation has led to debate among fans as to whether Sukuna's use of this ability was a plot convenience or a reflection of his character traits.
The main explanation for Sukuna's knowledge of the Reverse Cursed Technique projection may be due to Gege Akutami's decision in the story. Sukuna's intention to take over Megumi's body made it possible for him to possess this ability to aid in his plans.
While Sukuna's main goal is to save Megumi for future possession, the curse reversal magic provides a practical means of doing so, showing that he can use this technique to remove the curse with ease.
Sukuna's disdain for the Curse, shown in his encounters with characters like Mahito, supports the idea that he has learned the Curse Reversal Technique to deal with the Curse more effectively.
Given his status as the most powerful mage in history, Sukuna had reason to believe that he would master techniques that would allow him to remove obstacles, including Curses, with minimal effort.
Sukuna's interest in Megumi Fushiguro also plays a major role. Megumi, as a member of the Zen'in clan, can use powerful Cursed Techniques, including summoning Shikigami.
Sukuna realized the potential of these abilities and aimed to use Megumi as a vessel by having Yuji Itadori eat his finger and eventually forcing Megumi to do the same. This plan culminated in Sukuna being able to defeat Satoru Gojo using Megumi's body, with Shikigami such as Mahoraga playing a major role in their battle.
Ultimately, Sukuna's use of Reverse Cursed Technique projection in the series may be primarily a narrative choice by Akutami to facilitate the plot, allowing Sukuna to save Megumi for his own ends. However, it also fits Sukuna's character, reflecting his pragmatic approach to defeating the Curses and achieving his goals.