[valbaca]

Can OP just keep charging them? As in build in a recurring rate into the contract.

If they ghost, you keep charging them until they decide to cancel the contract.

Just like how a doctor will charge a cancellation fee, you could probably do that as well / instead.

Or up-front payments for x classes.

[reustle]

English teachers are a dime a dozen in Japan and are treated like garbage because of it. I doubt she has much sway over her contract.