Second season of . Mizuha, a high school second-year, is having the worst seventeenth birthday ever. She's missing her chance to get close to the older student she admires, and her parents didn't even remember that it's her birthday. Worst of all, there's a new and unknown infectious disease making the rounds, so all her club tournaments and school trips have been canceled. She's convinced that she'll never have the dazzling youth that she's always dreamed of... but then her childhood friend, Mizuki, suddenly declares himself a candidate to be her boyfriend. This is a school youth story about four childhood friends who grew up like family, one being the heroine, Nishino Mizuha, and the four boys she grew up with whom she sees as family.

By the mid-21st century, Tokyo's criminal underworld is ruled by Demon Lords—crime bosses who have undergone ether enhancement surgery, granting them terrifying superpowers. The only ones who can take them down are Heroes, bounty hunters who boost their own ether powers using the drug E3 (E-Three). With legalized killing as part of the job, being a Hero is less about justice and more about survival. Yashiro, known as the Reaper, is one such Hero—an independent enforcer who works alone. That is, until Jougamine, a high school girl and self-proclaimed "apprentice," forces her way into his life. Reluctantly taking her under his wing, Yashiro soon finds himself caught in a whirlwind of deadly conflicts.

Our hero wakes up one day in a brand new world…but his new life doesn’t come with fighting skills or magic powers, or even arms and legs! He’s reborn as a helpless egg, stuck in an unfamiliar forest surrounded by terrifying, hungry beasts. But eggs hatch, hatchlings grow up, and humble beginnings can lead to something great. He’ll do his best to become the strongest dragon ever, and no measly shell will get in his way!

I'm Rei Hitoma, a self-professed misanthrope thanks to some past trauma. Just when I thought my new teaching job in the mountains would provide a chill, rejuvenating environment, it turns out that this school is actually for demi-humans who want to become full-fledged human beings! There's a mermaid, a werewolf, a rabbit, and a bird...all of whom are now my charges. It's my duty to teach them about humankind—and maybe in the process, I'll learn a few things myself. This isn't an alternate world or a case of reincarnation. It's just the story of a teacher at a somewhat peculiar school, and his students who are striving to become human.