Hi there!
Yes, when you save Locally, it stores the data in your browser's storage (if you're on mobile or playing on Itch for security reasons).
If you play in Incognito that data will be deleted after closing the browser.
An alternative is to play directly on our official site htopia.online where you can select a folder in your file system's where you want to save your data when saving Locally. (This is only on PC and Chromium browsers such as Chrome, Edge, Opera). This would allow you to keep your save files in your PC and load them up in another device.
Another alternative is to get Cloud storage by becoming Harem Addict Patron.
Thanks for playing!