Nisshi has no company servers, no user accounts, and no analytics. Your journal lives on your device. If you want it on more than one device, you install the sync server yourself — on a machine you own.
Everything you write — logs, collections, locations you tag, attachments — is stored encrypted in the app's own storage on your device and on your Apple Watch. Nisshi does not upload it, index it, or send it anywhere for processing. The app works completely offline, and that is its normal state.
There is no Nisshi cloud to sign up for. If you want your journal on more than one device, you install Nisshi Sync Server on hardware you control. Your entries are encrypted on your device before they leave it, so the server holds only opaque ciphertext keyed by a random account id. It never receives your key and cannot read your content, titles, or history — and neither can we, because we never see any of it.
Nisshi asks for your location only at the moment you tag an entry with a place, and it is stored with that entry like any other text you write. There is no background location tracking and no location history kept outside your entries.
Export the whole journal as a single Markdown file, or write an encrypted backup you restore with your recovery password. Deleting the app removes your data from the device; if you run a sync server, its vault is a single file you delete yourself. There is no account to close, and nothing of yours is retained anywhere else.