Guru Guru Pon-chan volume 6
Ponta is a Labrador retriever puppy who uses the amazing Guru Guru Bone to transform into a human girl. She has fallen in love with Mirai Iwaki, who-after the initial shock-has overcome his concerns about her true canine form. So now the two are dating. But everything is new and different for Ponta, and she's having a rough (ruff?) time with the relationship.
When the Guru Guru Bone stops working its magic, Ponta finds herself trapped in her original dog form, and unable to communicate with Mirai. To make matters worse, there's a good-looking Labrador who has set his romantic sights on her! When the Lab's adorable owner starts spending time with Mirai, will Ponta be in the doghouse?