Not even the sonorous voices of 20 young children singing "I am a Noma Horse," was enough to put Erika, who really is a Noma horse, at ease.

Maybe she didn't like being lied to.

Or maybe this pretty little horse — a rare native breed that Ueno Zoo says "possesses a quiet demeanor (and) is good for working with children" — was simply nervous in the presence of the guest of honor, Princess Mako, 16-year-old daughter of Prince Akishino.