K-On! changed existence way of bishojo or moe anime in Japan by its friendly story, character, illustration style for not otaku people.(bishojo or moe means cute girl illust & characters)
Probably, the name “けいおん！K-On!” is known by almost all young Japanese people(Aside from whether they have seen or not).
I think that big hit of K-On is one factor of big hit of Kimi no Na wa in Japan.
けいおんK-On, Keion! = 軽音(Kanji) = 軽音楽keiongaku = light music
K-ON!’s music was light but made a strong impression many young people in Japan!