Kaiju Girl Caramelise Vol. 1 (manga)

Suffering from a rare, incurable illness that causes frightening changes to her body, loner Kuroe Akaishi spends her high school days avoiding her classmates--especially class idol Arata Minami and his groupies. But when Arata starts making her heart skip a beat with irritating regularity, Kuroe discovers that her illness actually has a big--make that MONSTER--secret: Romance turns her into Love-zilla...literally!