Sakura Matou is the awful Shinji Matou's super sweet sister. Unlike Shinji, Sakura is generous, helpful, but very unconfident. She spends a lot of time with Shirou at his house due to the state of things at her own home. In the Heavens Feel path of Stay Night her character goes down a much darker path. One of the sketches she's most prominently featured in is a parody of Japanese soap opera-like shows (contains a little bit of trigger-y content, so be aware)

For Sakura, try a very kind, sweet-sounding voice. Try one you feel like a really nice girl would have. The medium high range is probablt the right area to aim, but if you have your own approach, go for it.