I've always loved optical illusions, and I find amazing to have them done directly over the body of people. And the ephemeral aspect of her works make it even more interesting.
In her blog you can find a lot of other samples of her wonderful art, it deserves to be seen!
Update: I've just found that Hikaru Cho takes part in the Amnesty International's global campaign 'My Body My Rights'. I love her work for the campaign!