Mikami Satoru, a businessman, is stabbed by a criminal on the street and killed. When he regains consciousness in the darkness, he finds that he's been reincarnated as a slime! With nothing better to do, he spends his time devouring all the rare herbs and precious ores he comes across. As he does, he encounters the Storm Dragon Veldora, who was sealed in this cave 300 years ago by a hero's "Unlimited Imprisonment" skill. He's frightened at first, but as they talk, he becomes friends with the long-isolated Veldora.
I am one of only four True Dragons 
that exist in this world.
أنا واحد من التّنانين الحقيقيين الوحيدين
الأربعة الموجودين في هذا العالم
Ich bin ein Drache einer der
vier Drachenarten in dieser Welt.
Soy uno de cuatro Dragones Reales
que hay en el mundo.
Soy uno de cuatro Dragones Reales
que hay en el mundo.
L’un des quatre spécimens de dragons
qui existent en ce monde.
Sono uno dei soli quattro esistenti in questo mondo.
Sou um dos quatro Dragões Verdadeiros
que existem neste mundo.
Я один из четырёх
истинных драконов этого мира.