Yuuka is head over heels in love, and isn't afraid to tell anyone and everyone! She's sweet, has lots of friends and very overprotective of her boyfriend, Shinji! But is that sweetness just a cover-up for her secretly obsessive nature? 

I picture Yuuka with a medium sounding voice. Despite her being a feminine character, I can picture her with a fairly rough, raspy sounding voice? Something similar to this: https://www.google.com/search?q=iruma+miu+voice+lines&rlz=1C1CHBF_en-GBGB933GB933&oq=iruma+miu+voice+lines&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIICAEQABgWGB4yCggCEAAYhgMYigUyCggDEAAYhgMYigUyCggEEAAYhgMYigUyCggFEAAYhgMYigXSAQgzMTYzajBqN6gCALACAA&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:25ffbdd1,vid:ImOCymgLyB0,st:0 . That's just an idea though, if you think you've got a voice that suits better, give me your ideas!