Dragonbreath. [2], Attack of the ninja frogs / by Ursula Vernon.

Enhanced descriptions from Syndetics:

Danny Dragonbreath knew girls were trouble. But the new foreign exchange student, Suki the Salamander, is beyond trouble. Not only has she reduced his best friend, Wendell, to a blithering, lovesick tadpole, but she's apparently the object of an elaborate ninja frog kidnapping plot. Danny is never one to pass up an adventure (especially one involving ninja frogs), and so he and Wendell and Suki set out on a dangerous quest through the mythical Japanese bamboo forests to find out what these fearsome frogs want. Danny may not be able to breathe fire like a normal dragon, but he and Wendell have watched lots of kung fu movies and can totally take on a bunch of ninja frogs. Or, um, so he hopes . . .Using her trademark hybrid style of comic-book panels and text, Ursula Vernon has packed this second book in the hilarious Dragonbreath series with lots of kung fu, a little bit of loooove , and plenty of everyday school drama. A perfect fit for fans of Wimpy Kid and Bad Kitty .