Step one: download mematic
Step two: search for “gradient rainbow background” in Google images and pick one
Step three: go to this word art maker and be warned, every time you download an image you have to refresh the page because the merch ad appears without an x to click (have patience!)
Step four: find some stock photos, save them, and remove the backgrounds using this website
Step five: assemble
Joyralcos Japanese Striped Panties Bikini Cotton Anime Blue Pink Cosplay Underwear 2 Pack Briefs https://www.amazon.com/dp/B07DPTCP7Z/ref=cm_sw_r_cp_api_glt_fabc_12F147RX58FP5D2YB9J7?_encoding=UTF8&psc=1
This kigutumi is close to what you're looking for
Here’s a few links to some I found on amazon in case you’re interested! :)