You need to know how to put on kimono/yukata. There are lots of instructions and video tutorials but it involves some intellectual investment. The tutorials explain the different koshi himo ties and elastics you’d need to get along with the clothing as well as how to use tenugui towels. Dressing a prepubescent girl is generally rather easier than someone with all their eventual curves.

Saying that, there are acceptable cheat versions. We saw a version with different fabric choices in a shop within Disney Sea this summer. It comes as a long summer dress with shoulder straps. On top of this a “jacket” is worn and the bottom of the jacket forms a fake ohashori fold. I didn’t see if the half width obi belt was attached to the jacket part or if it is worn sperately. It was close to 20,000jpy
Just found it online: https://ure.pia.co.jp/articles/-/1938836


You’ll probably be able to find 3 part children’s Yukata in other places too.

Best place I know of for adorable and comfortable Japanese clothing is a company called Sou Sou who have branches in Tokyo as well as Kyoto. They also have an online store.
They have children’s Yukata with an integrated strap that makes it a bit easier to put on than a strictly traditional kind
https://www.sousou.co.jp/?wovn=en&mo...42735&csid=158

Their dresses are great and perfect for a sweaty body in the summer
https://www.sousou.co.jp/?wovn=en&pid=150214386

Sou Sou also has child and baby jinbei which are the ideal pyjamas/hot weather play wear.

15-17,000 is standard price for new children’s Yukata. Uniqlo sometimes sell them in Spring for the summer season, but usually not.

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Oh yes, age limit for dressing up at the Tokyo Disney Parks is 11. Those aged 12 and older are only allowed to wear costumes on very specific days with very specific rules.
https://www.tokyodisneyresort.jp/en/..._security.html