Do All the Big Guys Think I Am a Child of Luck?

Traveling through this world for 17 years, a high school student* has a beautiful girlfriend who is also a top student. I thought it would be a relaxed daily life, but I didn't expect that the world would change drastically, and countless monsters would emerge from the cracks in the space. What would happen in the end of the world? No, it's all heavens and realms! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.