High school student Issei Hyoudou is your run-of-the-mill pervert who does nothing productive with his life, peeping on women and dreaming of having his own harem one day. Things seem to be looking up for Issei when a beautiful girl asks him out on a date, although she turns out to be a fallen angel who brutally kills him! However, he gets a second chance at life when beautiful senior student Rias Gremory, who is a top-class devil, revives him as her servant, recruiting Issei into the ranks of the school's Occult Research club. Slowly adjusting to his new life, Issei must train and fight in order to survive in the violent world of angels and devils. Each new adventure leads to many hilarious (and risqué) moments with his new comrades, all the while keeping his new life a secret from his friends and family in High School DxD!

Simon and Kamina were born and raised in a deep, underground village, hidden from the fabled surface. Kamina is a free-spirited loose cannon bent on making a name for himself, while Simon is a timid young boy with no real aspirations. One day while excavating the earth, Simon stumbles upon a mysterious object that turns out to be the ignition key to an ancient artifact of war, which the duo dubs Lagann. Using their new weapon, Simon and Kamina fend off a surprise attack from the surface with the help of Yoko Littner, a hot-blooded redhead wielding a massive gun who wanders the world above. In the aftermath of the battle, the sky is now in plain view, prompting Simon and Kamina to set off on a journey alongside Yoko to explore the wastelands of the surface. Soon, they join the fight against the Beastmen, humanoid creatures that terrorize the remnants of humanity in powerful robots called Gunmen. Although they face some challenges and setbacks, the trio bravely fights these new enemies alongside other survivors to reclaim the surface, while slowly unraveling a galaxy-sized mystery.

Young Thorfinn grew up listening to the stories of old sailors that had traveled the ocean and reached the place of legend, Vinland. It's said to be warm and fertile, a place where there would be no need for fighting—not at all like the frozen village in Iceland where he was born, and certainly not like his current life as a mercenary. War is his home now. Though his father once told him, You have no enemies, nobody does. There is nobody who it's okay to hurt, as he grew, Thorfinn knew that nothing was further from the truth. The war between England and the Danes grows worse with each passing year. Death has become commonplace, and the viking mercenaries are loving every moment of it. Allying with either side will cause a massive swing in the balance of power, and the vikings are happy to make names for themselves and take any spoils they earn along the way. Among the chaos, Thorfinn must take his revenge and kill Askeladd, the man who murdered his father. The only paradise for the vikings, it seems, is the era of war and death that rages on.

Returning from their summer vacation, the students of Class 3-E at the prestigious Kunugigaoka Middle School find themselves up against unbeatable odds. Faced with the possibility of world annihilation, the students must come up with increasingly elaborate and creative ways to kill their teacher, the cunning yet optimistic and helpful Koro-sensei. However, eliminating Koro-sensei is not the only objective the students need to worry about. Gakuhou Asano, the academy's merciless and cruel principal, seeks to prevent Class 3-E's success by brainwashing his other hard-working pupils into ruthlessly competitive studying machines. Hostility begins to linger in the air as traitors and killers alike attempt to claim the bounty on Koro-sensei's head for themselves. Nagisa Shiota, one of Class 3-E's most skilled assassins, finds himself in the middle of the conflict. While he works to maintain his academic standing and prevent the end of the world, domestic affairs jeopardize his place in Class 3-E. Together with his dedicated classmates, he must now face the threats head-on.