I've heard about "Ring" TFs, especially the latex variant where as the ring goes up or down, it encases someone in rubber/latex until they are completely covered.

In this case, Yokana just so happens to step on one of those, causing her to be gradually encased in latex, until her appearance has changed entirely to become a rubbery Niko from Oneshot. Notably, the ring has since become part of her "hat" in that form as opposed to simply sealing her off in that form upwards.

She appears to enjoy the transformation and her new body as well.

Oneshot © Future Cat LLC, Team Oneshot