The Retired Hero is an Extra - Chapter 22 - : Flutter

While reading a book, a sparkle of light disappeared. And, as it did, a message appeared.

Roy died during a war against the Evil God Cult, but somehow, he returned back in time to 30 years in the past where he was just a boy who awaken his summoning magic.

Li Yi accidentally obtained a black science and technology library, which contains countless books of the inheritance of high-tech civilization and records countless knowledge.

There are thousands of bells in the book, there is a golden house in the book, there are many horses in the book, and there are Yan Ruyu in the book.

Li Yi has completely turned into a bookworm, learning all kinds of knowledge from the library, grand unified theory, particle Tebo theory, …, acquiring various black technologies, superconducting materials, super batteries, intelligent algorithms, … .

- Description from novelbuddy

“Only by enduring 2¹⁴ trials can one awaken the ancient power sleeping within the Key of the Star Prison, and become the most powerful being in the universe.”Timothy, the youngest Demon Lord in the history of his race, saw these words emerge after he touched the Key of the Star Prison, the most powerful artifact of the demon race, handed to him just before the old Demon Lord's death.According to the demon race's records, no Demon Lord had ever achieved this.However, over a span of a hundred thousand years, Timothy had easily passed 16,383 trials.Now, once again, he turned the Key of the Star Prison, and an unknown force mistakenly sent him to a brand new world, transforming him into an unknown and seemingly worthless demonic cultivator disciple.And the formidable opponent he was about to face in this world was the powerful Goddess Sylvia.When Goddess Sylvia received the challenge Timothy handed her, her cheeks flushed...“My dear Sylvia, I want you to know how deeply I love you. My heart belongs to you, now and forever.”