Free from the small press publisher @
iTunes (available to Canadians) & thence price-matched to selected regional
Amazon stores (will require a compatible level of app/device):
Draw Chibi Dark: Evil is the New Cute! by Christopher Hart, who's had a whole bunch of those Learn to Draw Manga and How to Draw Comics paperbacks out from arts instruction specialist imprint Watson-Guptill, IIRC. This is his niche instruction book in for Exactly What It Says In The Title, possibly self-published (it seems that Cartoon Crafts LLC only has the one e-book out from him thus far), if you're interested.
Learn to draw the dark side of the cutest characters in manga with Draw Chibi Dark—Evil Is the New Cute! In this ebook, bestselling how-to-draw author Christopher Hart gives step-by-step instructions on drawing two adorably dark chibi characters—a Goth rocker and a Victorian Goth. But don't be fooled by their spooky natures. These are still the unmistakably cute chibis that every manga artist loves.