Mushoku Tensei: Jobless Reincarnation

Mushoku Tensei: Jobless Reincarnation (also known as Mushoku Tensei: Isekai Ittara Honki Dasu) is a popular isekai fantasy anime (adapted from light novels) that follows a deeply flawed but determined protagonist.

In his original life, the main character is a 34-year-old Japanese NEET — an overweight, jobless shut-in who wasted his years after being bullied and becoming a recluse. One day, while trying to do something genuinely good for once (saving teenagers from a speeding truck), he dies in the process.

He awakens as a baby named Rudeus Greyrat in a completely new fantasy world filled with magic, swords, monsters, and adventure — but he retains all his memories and knowledge from his previous life.

Determined not to repeat his past failures, Rudeus vows to live seriously this time ("I'll go all out in this isekai!"). He starts training in magic from infancy (showing prodigious talent), builds relationships with his new family, learns swordsmanship, makes friends (and more), travels, faces dangers, and gradually grows both in power and as a person — though his past personality traits (including some pervy/awkward tendencies) don't disappear overnight.

The story is known for its detailed world-building, character development over time, emotional depth, and blending of adventure, family drama, comedy, and serious themes. It's often praised as one of the more mature and ambitious takes on the isekai genre.

The anime has multiple seasons/courts so far, covering his childhood, teenage adventures, major travels, and beyond.