Ryoma Takebayashi is a lonely middle-aged otaku businessman man who led a life filled with hardships until he dies from an unfortunate accident during his sleep. In the afterlife, he is greeted by three gods who grew fond of him and send him to another world as a child, where he makes use of his innate knowledge and abilities, combined with the gods' blessings to live a new life filled with challenges and happy meetings.
Equipped with magic, young Ryoma undertakes a carefree existence in the forest, leisurely learning more about his new abilities and surroundings. And when he encounters slimes like those in video games from his former life, Ryoma uses his newfound magical powers to get creative with his research! Will the gods get more than they bargained for in Ryoma?!
Three years go by. Having spent most of his time researching slimes, Ryouma has managed to evolve unique kinds of slimes, training an army of them while developing his magic abilities. Although the young boy is happy with his hermit existence and comfortable cave home, he somewhat misses the company of humans. But after healing an injured member of a passing group of travelers from a duke's household, Ryouma is persuaded to go with them and exit the forest accompanied by his menagerie of slimes. A whole new world awaits him, where his skills as a magic user and slime tamer continue to elicit surprise and admiration.