Lick_King said: I recall ZUN said he specifically asked Aki Eda not to draw Yuyuko with too big breasts.
Yuyuko however does canonically have big breast. ZUN just asked Aki not to exaggerate it. He mentioned before that Yuugi's breasts were a "Yuyuko level". The top 3 bust sizes at least according to ZUN would be Yuyuko, Yuugi and Yukari.
I'm under the impression when doing art for Touhou games, ZUN insists on minimizing curves... but when Alphes does something touhou yet not under ZUN's watch: Boobs. (Look at the Yuugi promotional, this, and the Komachi and Yuugi pics he posted recently, all have easily visible breasts)