Final script could see alteration to lines. 

Oguri's friend who is just along for her new training. 

Minor role with fewer lines. No real particular voice but a adorable and reliable voice might be more fitting. Any anime voice in her late teens to early twenties still works. Just don't sound to young or old and please no over the top cutesy voice. As long as you have a decent setup you'll be fine. Also feel free to do multiple takes and experiment with the voice.