Ah, high school. Is there any better place to start fresh after a horrible middle school relationship? Nope! Not unless your ex ends up at the same school as you and is now your stepsibling. What was supposed to be a sanctuary of peace where I could avoid ever seeing her again has become a living nightmare! Everywhere I look, I see her—in my house, in my school, in my class. There's no escape! She even claims that she's the older sibling. Like hell she is!

But I won't lose to her. After all, I'm the older brother in this new family situation. That's right, we're family now. No matter how much we may have thought we loved each other before, we saw one another's true colors and realized we weren't meant for each other. That's why even though we may keep up a buddy-buddy sibling act for the sake of our parents, things will never go back to the way they used to be.

A short, overweight student uses the Neuro Link, an evolution of the Nerve Gear, to escape himself from the reality. But his skills in the virtual world brings him to the attention of Kuroyukihime, a popular student who introduces him to the Brain Burst.

Considered a genius due to having the highest grades in the country, Miyuki Shirogane leads the prestigious Shuchiin Academy's student council as its president, working alongside the beautiful and wealthy vice president Kaguya Shinomiya. The two are often regarded as the perfect couple by students despite them not being in any sort of romantic relationship.

In the near future, a Virtual Reality Massive Multiplayer Online Role-Playing Game (VRMMORPG) called Sword Art Online has been released where players control their avatars with their bodies using a piece of technology called Nerve Gear. One day, players discover they cannot log out, as the game creator is holding them captive unless they reach the 100th floor of the game's tower and defeat the final boss. However, if they die in the game, they die in real life. Their struggle for survival starts now...

Kiyotaka Ayanokouji enrolls at the prestigious Tokyo Koudo Ikusei Academy, but is assigned to Class 1-D, where students with behavioral problems are housed. The school awards points equivalent to 100,000 yen per month and allows unusual freedom in classes, masking a more complex system.

A near future, where humans have been defeated by the viral parasites named Gastrea. They have been exiled into a small territory and live in despair, side-by-side in terror.

In this world trapped in darkness—

Rentaro, a boy living near Tokyo and member of the "Civil Security"—an organization specializing in fighting against the Gastrea—is used to accomplishing dangerous tasks. His partner is Enju, a precocious young girl. They fight thanks to their peculiar powers until one day, when they receive a special assignment from the government. This top secret mission is to prevent the destruction of Tokyo...

Set in a near future, this thrilling heroic-action story... starts now!