From the website, about the YFC tours;
「安全を規する為、ヒール靴・厚底の靴・上底の靴等は禁止とさせていただきます。
スニーカー等の動きやすい安全な靴でお越しいただきますよう、
皆さまのご協力を、お願いいたします。」
"For the sake of safety, please assume heals, platforms or above the ankle boots height inhancing insoles etc. are prohibited.
We request everyones' cooperation that they please come in trainers (sneakers) that are safe and easy to move in."
Well, that's my interpretation of it! And
excused_early corrected me; but please remember this is for Japan, this has not been posted for the EU tour - it's just something to think about for us all!
I'm pretty mobile in my Selia platforms though... >D
Big boots and platforms aren't a good idea (I'll still wear mine...), but if you're worried, invest in some double-soled Brothel Creepers like mine - they'll give you a bit of height with no risk to your ankles. (No high heel reference because I'm not a cross dresser XD)