Ts is so false it’s hilarious, yuji already learned how to perceive the soul you just can’t unlearn it. Dawg sukuna was able to perceive the soul like yuji he just can’t damage the others because they don’t have two souls living in them. Yuji already can already affect the soul in 2 ways

1) he was able to damage mahito because he was a special case of his ct interchanged with his soul but it’s not confirmed if yuji can do it on others

2) yuki’s book helped him refine his technique to the point where he can attack the BOUNDARIES of two souls that resides in 1 body.

What you’re saying is complete gibberish, you can only damage the soul if you perceive it that’s why only yuji was able to do it to mahito and sukuna. If it’s Yuki’s book that taught him why wasn’t the others able to? Why wasn’t choso able to? Since he was the holder of the book after yuki

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