By the Grace of the Gods 15 (Manga)

Slime's up for one recently deceased middle-aged businessman! When the gods reincarnate him in another world as a boy with magical powers, he discovers that magically tamed slime are an untapped natural resource!

When Ryoma tags along as an instructor for a rookie adventurers' field-training camp, the veteran instructors he's paired with offer him some advice: "You should rely on your companions."

Ryoma has certainly interacted with people since his reincarnation, but at his core, he's always...