A Thousand Worlds

People did not notice that the sky above them was torn apart. The space-time channel is quietly opening. The aliens are coming! The system called Thousand Realms gives people hope. With its help, contractors can travel through the fantasy world and gain strength. Devil Fruit, Giant Power, Blue Higanbana... All kinds of magical powers have become readily available. "My name is Lin Yu. I originally wanted to be a hero and save the beauty, but I succeeded half way." "It's fine, girl, I sent it." "Now an inexplicable system wants to sign a contract with me." "And invite me to... Demon Slayer: Kimetsu no Yaiba!"