Since Manabi had a special scheme for names, I went to check if names in K-ON had some cute gaglet attached. But according to ANN, it turned out to be a bit of pandering to fans of rock, or an inside joke at best:
The family names of the four main girls are named after former members of the disbanded band “P-Model”. In addition, the instrument used by each of the four girls also matches with the instrument used by the cooresponding P-Model member. Yui Hirasawa from Susumu Hirasawa (Guitar), Mio Akiyama from Katsuhiko Akiyama (Bass), Ritsu Tainaka from Sadatoshi Tainaka (Drum), & Tsumugi Kotobuki from Hikaru Kotobuki (Keyboard). In addition, there are other characters that have family names matching those from the band “the pillows”. They include: Sawako Yamanaka from Sawao Yamanaka (lead vocal & rhythm guitar) & Nodoka Manabe from Yoshiaki Manabe (lead guitar).
It’s a bit disappointing, but not too bad. Basically, Strike Witches redux.