Whoa. So you're probably feeling a tide of emotions at the moment, but just try to keep it together and focus on the bigger picture. The ad (it is an ad, in case you can't read Japanese), is for a cosmetics company called Shiseido, and revolves around the central tagline "Anyone can be cute."
And boy oh boy, does it deliver on that message.
The sexual ambiguity presented here is, on the most basic level, a cleverly executed advertising stunt. Beneath the surface, structurally and aesthetically speaking, it's extremely well-crafted and subtly brilliant at points. The opening shot is that of a painting -- basically, an illusion -- of a woman, before panning to a teacher who opens the door to a room full of the feminized young men. That same image is flipped upside-down (see what they did there?!) at the end. In addition to the strong focus on the flip book, the backtracking shot of the makeup application literally peels away the levels of femininity before our eyes, revealing the true nature of the subjects to the audience in an almost sensual fashion. To put it bluntly: it's a mindfuck.