Ochaco Uraraka is one of the more popular character's of this show but if you don't know too much about her, she's really passionate, hardworking and kind. So pretty much a youthful sounding voice. Honestly lots of these female character just sums it down to "a youthful sounding voice" haha. But ya know a voice that can convey her energy and how passionate she is. Again here is the wiki so you can do more research. https://bokunoheroacademia.fandom.com/wiki/Ochaco_Uraraka