The documentation does not mention any limitations:
«AlphaHPP» → «Paypage Request Reference» → «Request a Paypage Session»
But in practice, there are no payment gateways without such limitations, and the payment transactions with too big or too small amounts will fail, of course.
Is «10 JPY» to small?
Is «50000 USD» to big?
How can I know it in advance, without the «try and fail» approach in live production merchant stores?