This book is also known as The Invincible Life of a Second Rebirth or What to Do When Your Transmigrator's System Explodes
The boy was a transmigrator. After accidentally transmigrating to another world, he was born safe and sound with a System. He spent decades cultivating in seclusion, never causing trouble or picking fights. Many years later, just as he thought he was invincible and could travel wherever he pleased...
Then... the System exploded!
When he opened his eyes again, he had been reborn in a new fantasy world. This time his father didn't care for him and his mother didn't love him. He'd arrived on the scene at the highest difficulty level. The one thing he could be glad about, though, was that he'd kept the level he'd gained in his previous life!
Just as the boy was preparing to sever all ties and set off on the road back, however...
A noblewoman rushed over and pulled him into her arms, promising that Mom would take good care of him from now on. The young woman beside her raised a greatsword and said, "Big Sis, I'll protect you from now on!"
What was going on? Had his memories gone wrong? Wasn't I... someone people hated?
Was I... actually popular?
