Adapted from a manga by Kakifly, K-On! made its small screen debut in 2009. Besides a TV sequel in 2010, the franchise also includes a movie in 2011, and a number of OVA and music albums over the years.
The title 天使にふれたよ literally means I touched an angel. If not mistaken it’s from the last episode of the second season, it’s a pretty touchy song.