MTL - Supreme Demon - Chapter 3474 Asked comprehensively!

Heartbreak was the worst thing Kanata thought he’d face this week. He was wrong.When the world begins to rot and the dead rise, survival becomes the only thing that matters. Trapped in a school turned slaughterhouse, Kanata finds himself side by side with unexpected allies—his sharp-tongued childhood friend, a fierce upperclassman with a blade, and a dangerously calm teacher with a mysterious past.With betrayal still fresh and the world falling apart, Kanata isn’t looking to be a hero. He just wants to stay alive.But in the apocalypse… staying alive is the hardest part.

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates

There were five heroes who fought against Erebos, the primordial evil that drove the world to the brink of destruction. [Brave] Aron. [God’s Blacksmith] Dweno. [The Founder of the Nebula] Luna. [King of Wisdom] Risinas. Lastly, me [The Hero of Beginning] Kyle. When I was reincarnated 5000 years later, everyone was praised as a Legendary hero. “Except me.” A gift from God that records the achievements of heroes. The Hero Academy with Hero Records. Let’s go there and find out why.