The paquebot UPU regulation was introduced in 1894 and replaced other markings.
Check for paquebot literature here:
https://pbbooks.com/The paquebot regulation refered to ships without a ship post office (so NO selling of stamps aboard, passengers pocket stock) but offered collection of mails.
Either with a moveable postal pillar (placed on a quay before sailing) or by entrusting the mail from the passenger directly to the paymaster.
Acceptable stamps were those of the country of departure, the country of the vessel and the first foreign port of landing, where the mails were entrusted to the port post office.
In this case, DEI or Japan stamps would have been OK