Kimusume Renai Kinshirei

Hachiro, a rebellious delinquent boy, is always being mean towards Karen, an orphaned girl who has lived with him since childhood. However, his true feelings aren't what they seem. Hachiro has his own reasons for not wanting Karen to fall in love with him. Because when Karen falls in love, she turns into a demon... (Source: Comic Ryu, translated)