The five-girl band Hōkago Teatime from the K-ON!! anime series became the first anime characters to top Oricon survey firm's weekly singles chart. Not only did Hōkago Teatime's "Go! Go! Maniac" opening theme song for K-ON!! reach #1 for the week of April 26-May 2, but Hōkago Teatime's "Listen!!" ending theme song for K-ON!! ranked #2 for the same week. The band is only the third female act to ever rank one-two simultaneously on the chart and the first to do so in 26 years; Keiko Fuji accomplished that feat in 1970, and Seiko Matsuda did it in 1983.

Other anime characters have "recorded" singles that have reached #1 on the daily singles chart, and Hōkago Teatime had already reached #1 on the weekly album chart last July. However, no anime characters had sustained enough sales of CD singles for an entire week to top the weekly singles chart. "Go! Go! Maniac" and "Listen!!" had been #1 and #2 on the daily singles chart for six straight days since April 27 — all but ensuring that they would also top the weekly singles chart.

K-ON!! is the second television anime series based on kakifly's K-On! four-panel comedy manga about a group of high school girls who form a band. Voices actresses Aki Toyosaki (Yui Hirasawa), Yōko Hikasa (Mio Akiyama), Satomi Satou (Ritsu Tainaka), Minako Kotobuki (Tsumugi Kotobuki), and Ayana Taketatsu (Azusa Nakano) perform as their respective characters in the anime's soundtrack and the related CD releases.