The Ninja Club sleepover

"Willa and her best friends, Val and Fiona, love ninjas. They have matching ninja backpacks and ninja t-shirts, and they play Ninja Club every day. But Willa knows she's very different from her friends. When Val plans a sleepover for her birthday, Willa is excited--and nervous. The sleepover is on the night of the full moon, which will reveal Willa's deep, dark secret"--Provided by publisher.