Наступил последний год обучения для основателей клуба лёгкой музыки: Юи Хирасавы (平沢 唯), Рицу Тайнаки (田井中 律), Мио Акиямы (秋山 澪) и Цумуги Котобуки (琴吹 紬).

Вместе со своей младшей участницей Адзусой Накано (中野 梓) они проводят послешкольное время за чаем, поедая всякие сладости и порой репетируя. Помимо репетиций, выбора профориентации и поиска новых участников клуба у них множество и других школьных дел, но всё же они всегда находят время и для «After School Tea Time».

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!

[Written by MAL Rewrite]