Satoshi is [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka)'s younger brother. He appears when [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) is walking home with him from the movies. He then ventures of with a friend from school he saw on the way home. He seems to respect his sister [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) but still acts like a normal boy. 
Satoshi seems to be a bit more mature than [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka), usually saying things like "Geez, be more careful next time" when he has to take care of the problems she caused. Satoshi knows Mio because she and [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) have been friends for so long, but becomes shy when [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) brings the rest of the Light Music Club home without telling him ([Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) supposed it as a "rebellious phase"). He is also curious about his sister's doing and eavesdrops sometimes at her door (for example, when Mio and [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) were practicing for their class play, [Ritsu](https://anilist.co/character/19567/Ritsu-Tainaka) finds out that Satoshi is laughing outside her room as she practices her dialogue). He also dislikes cold weather. Although he sometimes laughs about his sister or tells her to be quiet when she practices in her room, he still respects her and asks her for permission to hang out with his friends.

Hirasawa Yui, a young, carefree girl entering high school, has her imagination instantly captured when she sees a poster advertising the ‘Light Music Club’. Being the carefree girl that she is, she quickly signs up. However, Yui has a problem, she is unable to play an instrument. 
When Yui goes to the clubroom to explain, she's greeted by the other members: Ritsu, Mio and Tsumugi. Although disheartened at Yui’s lack of musical know-how, they still try to convince her to stay to prevent the club’s disbandment. After playing Yui a short piece which re-ignites her imagination, they succeed in keeping their new member and guitarist. 
Along with the tasks of school and homework, Yui begins to learn the guitar with the help of the other band members, experiencing many mishaps along the way. However, with the school-festival drawing near and Yui getting stuck with her practice, will the Light Music Club be ready in time for their debut? 
(Source: MAL Rewrite)

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!
 
(Source: MAL Rewrite)

With graduation right around the corner, every member of the Light Music Club except for Azusa will be leaving for good. But the girls aren’t going to let something as silly as graduation tear them apart! For their final hurrah, the girls are going on the ultimate vacation tour— all the way to London! Their overseas journey will lead them on a trip of discovery and friendship as they take the stage one last time for their final encore together. 
(Source: Sentai Filmworks)

A special episode of K-ON!! released in the ninth volume of Blu-ray and DVD. The girls plan a trip abroad and go to the passport office to apply for passports.

Satoshi Tainaka