[1] Hiiragi was born in Fukuoka (which became Kamifukuoka in 1972 and then Fujimino in 2005), Saitama Prefecture, Japan, and grew up in Mibu, Tochigi.
She created a number of other manga over the next two decades, including Hoshi no Hitomi no Silhouette and Gin'iro no Harmony.
Hiiragi's most widely known work is Whisper of the Heart, a manga which was later made into an anime film by Studio Ghibli.
[2] Two cats in the film, the Baron and Muta, have appeared in five different Studio Ghibli productions.
Studio Ghibli commissioned another story from Hiiragi involving the cats as more central characters, which became Baron, Neko no Danshaku, also released as The Cat Returns.