A Summary:

The country of Ramol has been at war with Oto for years now, and has remained at a stalemate for many years. In a desparate search for a way to end the conflict, Ramol turned towards summoning magic, and began to beat back the Oto forces with the power of demons and various other beings summoned from different realms. That is, until Oto made a massive change of its own, and halted the streams of incoming soldiers in one particularly bloody battle. It was during this battle that one of the summonings went awry. No one could have guessed who would walk out of that portal, and none could have guessed what effects he would have on this world. Least of all the man himself.

Another Summary:

Leo was walking down the street when he was summoned to another world entirely, and not in the idea that he was 'summoned to another world to be the hero,' or anything even remotely close to that scenario. No, it is more like he fell through an inter-dimensional crack into a world with cosmic laws very unlike Earth's, and as he fell he just so happened to be captured by the summoning ritual of an army. As if that wasn't bad enough for a first impression, after escaping from the battlefield his situation just seems to get worse and worse as he realizes just how different this world truly is. In this world, it truly is a case of having an 'uncaring god' in the form of the ever-apathetic [System].