By the Grace of the Gods (manga) 12

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! Gimul will soon be celebrating its founding with a festival, and Ryoma decides to participate by opening a food stand with his Bamboo Forest workers. They''ll be serving some special dishes from the varied hometowns of Ryoma''s employees. As excitement builds up for the festival, a potential problem arises when giant ants threaten the road to Gimul. In response, Ryoma takes a job with the Tamer''s Guild and deploys his army of birds and slimes to search and destroy the dangerous ants!