Little Unicorn Is SadMr. Men meets The Color Monster with a unicorn! in the third book in this series that taps into the current trend of books about childhood emotions, this one about sadness. A little unicorn's rainbow colored mane shifts to a single color when he's feeling a particularly strong emotion. It seems like a storm comes over him when he's sad, and his mane turns deep blue. But when he repeats a breathing exercise, the clouds clear and his rainbow returns and