Many anime mentors, of course, are among the strongest characters in their respective series. In that case, there's nobody else better for the protagonists to learn from than the best of the best. Some anime mentors, however, are stronger than the rest.
Jujutsu Kaisen's Satoru Gojo is a wunderkind in the world of jujutsu sorcery. He was born with both the Six Eyes and Limitless techniques, making him the first in 400 years to possess both. It's said that Gojo's birth altered the universe's balance for the first time in centuries. Cursed spirits and curse users were forced into hiding because someone was out there, ready to defeat them at any moment.
Gojo's cursed techniques are some of the flashiest and most electrifying in Jujutsu Kaisen. Just to name one, his Domain Expansion: Unlimited Void traps his enemies in a metaphysical atmosphere where they're simultaneously inundated with everything and nothing. Most would have expected Gojo to subject Yuji to brutal cursed energy training, but fans loved that he likened honing one's flow to cursed energy to mindfulness while doing other tasks, like watching movies.