Hotaru

Hotaru is a middle school student as well as Miki's best friend and age switching partner.
   From a pretty rich family, Hotaru is acting as an exemplary girl, student and daughter, to the point she doesn't even know how to have fun. Luckily, she got closer to one of her classmates, Miki, thanks to the age switching power they coincidentally discovered they share. 
   A little quiet, shy and kinda timorous, Hotaru is more introvert than her friend Miki. She's really cautious about everything and appears reluctant to most of Miki's plans, knowing she will be dragged into some crazy stuff again. But despite their opposite personalities, Hotaru sincerely likes and trusts Miki. 
   Hotaru has a big amount of domestic pets where she lives, but is oddly scared of other pets than them.