Koizumi was born into a musical family, with both of her parents and grandfather having music-related jobs. She also has an older sister who works as a model in Osaka, whose stage name is Licca.[3]
She is described as shy and modest, but sometimes a playful person who is rather independent. She says that she relates to her Revue Starlight character Nana in that she is always preoccupied with her cast-mates' well-being.[citation needed]
Along with costar Haruki Iwata, Koizumi is part of the musical unit "harmoe".[4]
