Happy!? Sorry!! - song and lyrics by Sakurakou K-ON Bu

Mio Akiyama, K-ON! Wiki

K-On! (TV Series 2009–2010) - IMDb

K-ON! Shuffle, Vol. 1 ebook by kakifly - Rakuten Kobo

a cosplayer doing Yui Hirasawa from the anime k-on Stock Photo - Alamy

K-ON!

Review: K-ON! – AniB Productions

Masterpiece Anime Showcase: K-On!!, Appreciating Everyday Life at After School Teatime and The Road to Graduation At the Nine Year Anniversary

File:Mirai Suenaga with summer school uniform and K-on character style 20110305.jpg - Wikimedia Commons

Don't Say Lazy (From K-On!) — Sakurakou K-ON Bu

Nendoroid Petite Petite: K-ON! (The First) - NendoGuide