Invincible With My Three Sisters

2025 is the year that portals to the Desolate Land appear in various places on earth. This is a ruined world and a world where technology doesn't work but has things that only exist in a fantasy world. Magic power, giant monsters, titans, ancient tombs, and all kinds of strange treasures, all things exist in this world. 25 years after that, civilization has changed along with the fate of many people. Some people get lucky, become a dragon in one step. Unfortunately, our main character, Arthur, doesn't have too much luck. His parents died in an unknown place, leaving him with no one. When he was 11 years old, his body somehow suddenly became sickly often, he often felt weak and could only be normal if he took medicine. The wealth that his parents left for him was used up to buy medicine, he even had to sell the apartment where he lived. He became homeless and things only got worse. However, that was not the end of his life. A luck he never imagined suddenly came to him. In the middle of the cold night, three extremely beautiful female figures appeared in front of him. One of them said, "Little brother, sorry for making you suffer all this time, from now on we will help you become the highest among the highest."