Naruto vs Honkai Impact 3rd
Connection:
Both are calm and collected mentors who're heroes from a previous large scale event (Third Great Ninja War and Previous Era respectively)
Both are part of team (Team Minato and Thirteen Flam-Chasers respectively) and were great friends with one of their team members (Obito Uchiha and Kevin Kaslana respectively), only for them to turn to the dark side after a tragic event (Obito witnessed Kakashi killing Rin, whereas Kevin sought to destroy humanity to save them after witnessing is lover Dr. MEI die from Honkai poisoning in their fight against the Previous Era's Herrscher of Finality)
Both would also have an admirer from their younger years(Sakumo Hatake and HIMEKO from the Previous Era) only for them to die in front of their very eyes (Sakumo committed suicide after being ridiculed for prioritizing his friends over a mission, whereas HIMEKO became the Herrscher of Fire who was killed by Kevin), which left them cold and bitter
Both would join another group (Anbu and Schicksal respectively) and took up a new role (Kakashi becoming a Jonin squad leader and Fu Hua becoming Class Monitor), in which they'll become mentors to a major squad trio (Team 7's Naruto Uzumaki, Sasuke Uchiha and Sakura Haruno & Squad V's Kiana Kaslana, Raiden Mei and Bronya Zaychik) in which their cold demeanor began to warm up
At one point, both would be killed by a major antagonist (Pain and Otto Apocalypse) but would be resurrected later (Kakashi being revived by Nagato after Naruto talked to him personally and Fu Hua being revived by Otto only to break out and escaped)
Both would also assist in confronting their former friends and would later assist in defeating one of the final villains of their series (Madara Uchiha and Kevin Kaslana respectively), who ended dying peacefully after learning the error of their ways