The recent translated ch 2 of this manga have the busty 28 years old shopkeeper regressing in age with pretty gradual process, there are raws out there for more process as it seems she switch between ages but seems to be behind a paywall.
ENG:
https://mangadex.org/title/42953/mys...disappearances
RAW:
https://yawaspi.com/kamikakushi/index.html