After vanquishing another boss and stepping through the gates of the fifth floor, the misfit duo Kazuto Kirito Kirigaya and Asuna Yuuki are greeted with a beautiful landscape of crumbling ruins and catacombs steeped in mystery. This idyllic adventure is short-lived, however. Tensions between the Dragon’s Knights Brigade and the Aincrad Liberation Squad—the two leading guilds focused on clearing Sword Art Online—continue to rise and threaten the fragile stability of the frontline raiding group. Kirito and Asuna are forced to act quickly, making a desperate gamble and gathering a small number of allies for a dangerous mission. As a result, Asuna and Misumi Mito Tozawa must come to terms with their relationship after the near-tragedy that forced them apart on the first floor.

Ren Mihashi was the ace of his middle school's baseball team, but due to his poor pitching, they could never win. Constant losses eventually lead to his teammates bullying him and reached the point where his teammates no longer tried to win, causing Mihashi to graduate with little self-esteem. As a result, Mihashi decides to go to a high school in a different prefecture where he has no intention of playing baseball. Unfortunately, upon his arrival at Nishiura High, he is dragged into joining their new team as the starting pitcher. Although unwilling at first, Mihashi realizes that this is a place where he will be accepted for who he is; with help from the catcher Takaya Abe, he starts to have more confidence in his own abilities. Abe, seeing the potential in Mihashi, makes it a goal to help him become a pitcher worthy of being called an ace.

Takeru continues his education at Tenbi Academy as part of the newly formed Security Committee. As a team with the other members, they battle unscrupulous individuals who use their Maken for evil purposes. In the meantime, his libido and the conflicting romantic interests of the girls surrounding him complicate matters considerably. (Source: ANN)

Bundled with the 5th, 6th, 8th, 9th, 12th and 13th limited-edition volumes of the manga.