This little set of prints must have been produced in 1933, the year that the Emperor Showa (known as Hirohito in the west) had a son. The prints are of a type usually referred to these days as マッチラベル (match labels), because of their similarity in size to the matchboxes that were common in those days.

Prints of this type though, were not directly related to matchboxes, but were created and distributed by collector's groups, of which there were many. The collectors would have a number of meetings each year, at which they would plan their next productions. Concepts and design ideas would be arrived at by discussion, and then when the new project was decided, a local print-making workshop would be contracted to do the production. The members would of course all be levied a fee, and when the prints were finished, each member would receive a set.

Designs were occasionally prepared by the group members, but more commonly by professionals hired for the task. In many cases, the names (or nicknames) of the members appear on the prints, but this example - being produced in commemoration of the birth of the new Crown Prince - does not have those.

What you are seeing here is the envelope (also woodblock printed) which the six little prints came in. It has also been taken to the Post Office to receive a commemorative franking, showing the date of the prince's birth.

This particular little print set was featured in one of the 'David's Choice' YouTube videos in February of 2019.