Haruyuki Arita is an overweight, bullied middle schooler who finds solace in playing online games. But his life takes a drastic turn one day, when he finds that all his high scores have been topped by Kuroyukihime, the popular vice president of the student council. She then invites him to the student lounge and introduces him to "Brain Burst," a program which allows the users to accelerate their brain waves to the point where time seems to stop. Brain Burst also functions as an augmented reality fighting game, and in order to get more points to accelerate, users must win duels against other players. However, if a user loses all their points, they will also lose access to Brain Burst forever. Kuroyukihime explains that she chose to show Haruyuki the program because she needs his help. She wants to meet the creator of Brain Burst and uncover the reason of why it was created, but that's easier said than done; to do so, she must defeat the "Six Kings of Pure Color," powerful faction leaders within the game, and reach level 10, the highest level attainable. After the girl helps Haruyuki overcome the bullies that torment him, he vows to help her realize her goal, and so begins the duo's fight to reach the top. [Written by MAL Rewrite]

One fateful day, Yuusuke Urameshi, a 14-year-old delinquent with a dim future, gets a miraculous chance to turn it all around when he throws himself in front of a moving car to save a young boy. His ultimate sacrifice is so out of character that the authorities of the spirit realm are not yet prepared to let him pass on. Koenma, heir to the throne of the spirit realm, offers Yuusuke an opportunity to regain his life through completion of a series of tasks. With the guidance of the death god Botan, he is to thwart evil presences on Earth as a Spirit Detective. To help him on his venture, Yuusuke enlists ex-rival Kazuma Kuwabara, and two demons, Hiei and Kurama, who have criminal pasts. Together, they train and battle against enemies who would threaten humanity's very existence. [Written by MAL Rewrite]

Yearning to make friends and perform live with a band, lonely and socially anxious Hitori "Bocchi" Gotou devotes her time to playing the guitar. On a fateful day, Bocchi meets the outgoing drummer Nijika Ijichi, who invites her to join Kessoku Band when their guitarist, Ikuyo Kita, flees before their first show. Soon after, Bocchi meets her final bandmate—the cool bassist Ryou Yamada. Although their first performance together is subpar, the girls feel empowered by their shared love for music, and they are soon rejoined by Kita. Finding happiness in performing, Bocchi and her bandmates put their hearts into improving as musicians while making the most of their fleeting high school days.

It is the new year, which means that the senior members of the Light Music Club are now third-years, with Azusa Nakano being the only second-year. The seniors soon realize that Azusa will be the only member left once they graduate and decide to recruit new members. Despite trying many methods of attracting underclassmen—handing out fliers, bringing people into the clubroom, and performing at the welcoming ceremony—there are no signs of anyone that plans to join. While heading to the clubroom, Azusa overhears Yui Hirasawa say that the club is fine with only five people and that they can do many fun things together. Changing her mind, she decides that they do not need to recruit any members for the time being. K-On!! revolves around the members of the Light Music Club as they experience their daily high school life. From rehearsing for concerts to just messing around, they are ready to make their last year together an exciting one!