Naruto: The Outsider's Resolve - Chapter 3.9 (098):

“A modern online novel writer who had been struggling finds themselves transported into the world of One Piece, becoming a 10-year-old child.After a series of events, Ryuen arrives at Cocoyasi Village. The protagonist possesses the Tori Tori no Mi (Bird-Bird Fruit), Mythical Zoan type, Phoenix form.After undergoing a rebirth (Nirvana), the protagonist's transformation no longer involves turning their hands into wings, and the fruit's power becomes even stronger!From the moment they reach Cocoyasi Village, the protagonist and Nami embark on an adventure, traveling from island to island, indulging in food, drink, and fun. Along the way, they also help the poor by taking from the rich, because, after all, Bellmere’s family is still...”

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.

A spin-off of the various works of Kamachi Kazuma. One day, Kamijou Touma (A Certain Magical Index) faced yet another misfortune. His toilet was broken and spraying water everywhere. As he was lamenting his misfortune, suddenly he appeared in a strange place along with Index and Misaka. Soon enough, more strange people begin appearing…

Includes:

A Certain Magical Index

Heavy Object

The Zashiki Warashi of Intellectual Village

The Circumstances Leading to Waltraute’s Marriage

A Simple Survey / A Simple Monitoring

Killer Princess and Deep End

Sam crosses to a new planet that is completely magical. He discovers that humans can have superpowers, and monsters also inhabit the planet. Humans continuously fight these monsters to protect themselves and their world.Unfortunately, Sam, who just arrived on the planet, lacks the potential to become powerful and doesn't possess any shortcuts to gain strength quickly. As a result, he resigns himself to living an average life and tries to avoid danger.However, everything changes when he graduates from the academy. He receives an invitation from his former academy to become a teacher, and simultaneously, he awakens the Teacher system.Now, on this perilous planet, if he desires to become powerful, he must accept students and empower them. Only when his students become strong will he gain strength himself. Join his journey to become the greatest teacher.