MC, his little sister, and along with her classmates were summoned to Another World as Heroes. As expected, the Princess request their help in subduing the demons. Same old, same old.
Thankfully, the MC didn't believe her words. Just as he was looking for information of this unknown world, he came across someone, which caused him to seek out the King, asking for permission to leave the castle. Surprisingly, the King give him permission.
And so, MC and his little sister left the castle with goal in mind.