Kaiju Girl Caramelise Series by Spica Aoki

Suffering from a rare, incurable illness that causes frightening changes to her body, loner Kuroe Akaishi spends her high school days avoiding all 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!

All Kuroe Akaishi wants is to live a low-profile life without inconveniencing the residents of Tokyo...That's why she's been maintaining a loner life, after all. But with class heartthrob Arata Minami in the mix, her uncontrollable emotions threaten to wreak havoc on the city once more! What's a lovestruck monster gotta do for a normal love life?!

As if magically transforming when she gets nervous weren't enough, high school girl Kuroe also has to survive the twists and turns class heartthrob Arata causes through their...acquaintance? As the new semester approaches, a new face brings a mountain of new problems along...

Kuroe finally mustered up her courage and kissed Minami...in her kaiju form! Now that he's the hot topic of the national media, it's the job of the newly dubbed “Kaiju Prince" to protect his human girlfriend from the press. But with the delicate balance of the Minami-Kuroe/Harugon-Manatsu love triangle ruined, can their fragile relationship survive the scrutiny of the media—and the jealousy of their friend?

She loves him. Kuroe definitely loves Minami...right? But Minami's popularity, his insistence that they keep their relationship a secret, her attempts to hide her nature as a kaiju from him-it's all starting to crush her spirit. So when a small misunderstanding snowballs into a fight between them, Minami's refusal to really listen to her is the last straw! Maybe they weren't meant for each other after all...