Update - October 27th 10:00am: The Tokyo Comic-Con has reversed its ban on male cosplayers dressing as female characters.
This December, the Tokyo Comic-Con kicks off. The event should be similar to its San Diego counterpart, attracting celebrity guests and hordes of cosplayers. However, at the Tokyo event, there’s a significant difference: Men cannot cosplay in women’s clothing.
As Anime News Network points out, the official site clearly states such under the “regarding cosplay outfits” section, writing that is “prohibited” for men to wear female clothing (男性による女装は禁止です). The ban uses the Japanese word “jyosou” (女装), a word which is defined as “wearing female clothing” and which has the explicit nuance of referring to men wearing women’s clothing.
Japan has a long history of men dressing as women. Heck, kabuki theatre does not have actresses and all the women are played by men...wearing female clothing. But as ANN explains, this sort of ban at otaku events is relatively common in Japan, because organisers worry about large numbers of men dressed as women showing up.
The Tokyo Comic-Con will feature appearances by Jeremy Renner, Matthew Lewis, and Stan Lee. As of right now, it will not feature male crossplay.