Minato Namikaze was a formidable opponent. With the Flying Thunder God Technique and a vast array of Sealing Jutsu at his command, he was a ninja no one could take lightly.
In the real world, Minato served under Uchiha Yi, and Yi had overseen his training. No one knew Minato better.
Yi had even taught Minato the Flying Thunder God Technique himself.
Yi had also given him pointers on Sealing Jutsu whenever he had time to spare. Mito Uzumaki occasionally taught larger classes, too. As one of the village's most gifted young talents, and given his position, Minato naturally qualified to attend.
Defeating Minato would be difficult, even though Yi had begun to step into the so-called Six Paths realm.
But Yi had a Dōjutsu devastating against weaker opponents: Limbo: Border Jail.
Against Six Paths Level opponents, Limbo: Border Jail was of limited use. Against weaker foes, though, Yi considered it the strongest Dōjutsu there was.
A shadow ordinary people could neither see nor sense was deadly.
Only someone with the Rinnegan could see those shadows. Someone who had mastered Six Paths Sage Mode could sense them as well.
Ordinary Sage Mode could not sense them either. What could be better than Limbo: Border Jail for crushing a weaker opponent?
Of course, Yi suspected that a Byakugan on Kaguya Ōtsutsuki's level could see through Limbo: Border Jail with ease.
Minato, even in Kurama Mode, had not reached that level. The Nine-Tails could sense good and evil, but he could not sense Limbo shadows. Minato knew Sage Mode, but his Sage Mode was not Six Paths Sage Mode.
In an instant, Yi kicked Minato, used a Sealing Jutsu to temporarily seal his Chakra, then brutally dislocated both his arms. Minato could no longer move or break the seal.
Yi's Six-Tomoe Rinnegan