From what I remember, the main character is summoned into a fantasy world. However, the twist in this manga is that he was already summoned to this world once before, but after he saved it, the king feared his power, so he forcefully reincarnated the MC back into our world.
In his second life, he was summoned back to the world he was summoned to before. Once he was summoned, he kept his powers a secret, which persisted with him through being reincarnated and the second summoning.
He meets his previous underlings, whom he taught how to fight among other things. Oh by the way, all his underlings are perverts and like to be disciplined by him. They wanted to see their master again, after he was forcefully reincarnated back to his previous world.