Authentic Meiji period original and authentic (c.1900), Japanese shunga woodblock prints.  It's a complete set of twelve different yearly event-themed shunga woodblock print pictures/envelope pouches.  The pictures speak for themselves if you look closely, as each and every one is sexually suggestive in one way or another.  
All pictures here are actuallly miniature woodblock print envelopes.  They come inside a larger ukiyo-e casing adorned with fireflies and the moon on the cover.  Larger shunga woodblock print case measures 11.8 cm x 6.3 cm when closed up.  The envelope pictures each measure 4 cm x 9 cm and are in very good condition, a few sporting some light foxing spots.  Very good colors and impressions.  No backing.  Please see and judge from photos. 
 
This is a very odd and rare set of sexually connotative artwork from c.1900 Japan.  Funny and cleverly crafted, Japanese festival and event-themed erotica.  These would also fall under the shunga woodblock print trick-picture-oddity theme.  So seemingly innocent, yet explicitly sexual in nature.