Sign-In Gacha System

You know... Life is full of surprises. One night, I'm just your regular office drone that tries to survive the capitalistic city where the rich, but it changes quickly. One night, I died. Yup, just like that. I died while sleeping. However, it was not the important thing. The most important thing is that I reincarnated into a fantasy world. That sounds good, right? No! I get reincarnated into the world where monster roams the land, and what makes matters worse is that I'm reincarnated as the son of a lord who defends the land from monsters. And that is not the worst of it all! I got a Gacha-based system! The bane of my existence!