Naruto: I Am Uchiha Sasuke!? - Chapter 43 - 42 The Gathering of Rivals

A man who was once called the world’s strongest agent ended up becoming a teacher after his retirement, to train a new generation of agents. After many years of training his disciples, he was killed at the age of 60 by a secret organization’s ruse and was reincarnated in another world with his memories intact. Though he was surprised by the existence of magic and the strange species in that world, he quickly adapted to his condition as a newborn and took advantage of it. He acquired special magic and gained a massive amount of strength thanks to his rigorous discipline, in order to reach his goal: Resume his career as a teacher which he left halfway through in his previous life. This is the story of a man, who, based on the memories and the experiences of his previous life, became a teacher who travels through the world with his students.

When gods gather, lightning will strike and the earth will move. Immortals! Which of the numerous way to immortality should one follow? Immortals are hard to seek, but why should immortals hide? Heaven has no mercy, but humans have emotions, and these emotions hinder the road to longevity!

Train the inner self to stay calm, train the external body to be resistant, then cross the three continents and four seas alone, and fight valiantly with demons and devils! With the heavenly baton in hand, raid the devils and demons without any resistance! Take one step to cross nine stars and chase the sword in the dreams! Traverse a thousand li of river and mountains in a single day! The exceptional beings do not mix with the ordinary! Within the universe, where can one find an obstacle! Moving like a dragon, with talent like a phoenix! The heavenly Daos and stars will guide one’s way!

- Description from Novelupdates

Kaito Nakamura, a shy university nerd, thought he’d found love when the stunning Aiko chose him as her boyfriend. Their sweet, fluffy romance fills his lonely world with hope—until he discovers she’s cheating on him with multiple guys, reveling in the taboo thrill of betraying someone so innocent. Heartbroken and humiliated as explicit photos of her circulate online, Kaito’s tears are interrupted by a mysterious popup: the “Revenge NTR System Beta.” Promising retribution but with a chilling condition — he can’t break up with her.Contains Ntr, read at your own risk

As a villainous demonic cultivator, isn’t it perfectly normal to take a fox demoness as a spiritual pet?As a villainous junior brother, isn’t it reasonable to make the cold and stunning senior sister reveal a shy side?As a villainous disciple, isn’t it my duty to melt the icy heart of my villainous master and save her from the abyss of corruption?…I was wrong.After they fell to darkness, they captured me and ruthlessly “repaid” their gratitude.