From Del Rey:
Ponta is a Labrador retriever puppy, the Koizumi family's pet. She's full of energy and usually up to some kind of mischief. But when Grandpa Koizumi, an amateur inventor, creates the Guru Guru Bone, Ponta's curiosity causes trouble. She nibbles the bone - and turns into a human girl! Now Ponta lives two lives: one canine and one human!

Winner of the Kodansha Manga Award for Shoujo 2000.

Yaya’s high school friends haven’t been very nice. They call her “Yaya the cry-ya! Yaya the misfi-ya!” But no matter how badly they act, Yaya is just too na?ve and trusting to believe the worst of her friends. Hard-rocking, butt-kicking Nana is just the girl to grab hold of Yaya’s timid demeanor and turn it upside down. Nana exposes Yaya’s “friends” as slime bags, doles out punishment, and does it all with style. Can there be anything that terminally shy Yaya and hyper-confident Nana have in common? Well, for one thing, they’re the same person.

-- Manga Updates

Because of her fathers job, Aki was raised in England. So when she moved back to Japan she was teased horribly for being "foreign". Now Aki is also a very beautiful young woman, which makes it even harder to make friends and be accepted. After the coolest boy at school starts taking an interest in her, things only get worse. As jealous girls start to harass her, Aki shows a side of herself that even she didn't know about.