Jikuu Mahou de Isekai to Chikyuu wo Ittarikitari - Chapter 363 - Fight!

This is a story about a legend, of one that can never be forgotten.
Summer, first time down the mountains in 16 years, after being raised by his 3 masters and Fairy sister.

‘Why won’t you follow the Rules of society?’ The rules are the tool made by the strong, so I follow my own rules.

‘Why won’t you just use your brain instead of your brawn?’ Idiot! Have you ever seen anyone use their brain, to get back at an ant that bites them!? No, they just casually step on it.

‘Oh, everyone says you’re a first-class beauty huh?’ well, I’m sorry but even you are not qualified to be my wife. Only a ‘Summer class beauty’ is worthy enough!

‘My enemy is sick?’ Oh, don’t worry, even if you’re on your last breath and I feel it’s beneath me to slap shot you dead. I’ll just fix you up and then beat you!

‘Who am I?’

“I am Summer in the spring, the autumn, and the winter, I’m the world’s first above the heavens!”

Follow me, Summer Day as I step by step become known as the world’s first master, the world’s first doctor, the world’s richest man…… a lot of other world’s number one, but most importantly, The worlds happiest man.

- Description from Novelupdates

(Third Person Limited PoV.)Betrayed by his fiancée, mocked by his siblings, and disowned by his family—that was Lev’s fate.Even when he regained memories of his life on Earth, where he realized that his world was strikingly similar to his favorite novel, it still didn’t help him change anything.How could it be?Because the protagonist of the story had already achieved his happy ending—gaining a beautiful wife and living a blissful life. Meanwhile, the world continued to move forward.What do people usually do with a novel that has ended? They tend to stop caring about the world within it, even if it falls into ruin, especially if the novel isn’t particularly popular.The world Lev Razanov lived in shared a similar fate—it was destroyed.[Hero’s System successfully installed.][Critical condition detected.][Do you wish to return to the past?]Lev was given a chance to return to a time when the story of his favorite novel had just begun.Although he was destined to become an extra villain—a pawn of the pawns serving the real villain, he vowed to end the lives of anyone who had caused him suffering: his siblings, his fiancée, the main character, or anyone else.[Hero’s System inherits your desire from your life on Earth—the desire to do good.]“Who said killing your enemies is an evil act?”

I returned to Earth as the invincible Knight King. But the Gods came with me.

An alien race invaded the Earth on June 6, 2128. At the midst of this war, many nations allied with the alien threat and the war nearly wiped out the rebelling humans of the planet. At the edge of mankind's survival, the United Nations Army launched its forces to eliminate the immediate stellar threats that loomed over Earth.

General Seeker Carlean, commander and leader of the mission, risked and gave his life to destroy the immediate stellar threat. The battle was won though Earth lay in ruins. Perhaps mankind will live to see a few years of peace before the alien threat returns to wipe out their existence.

At the immediate aftermath of the stellar battle, the fallen Seeker Carlean awakens and finds himself at aged 17, living the peaceful life he lived 16 years before he died.

So begins a new game in the battle for humanity's survival.