Authentic Edo period original, c.1842, Japanese shunga erotic art woodblock print by Kunisada Utagawa (1786-1865).  From the shunga series, Shiki no sugatami  (Viewing Forms in the Four Seasons). Shunga picture measures 24.5 cm x 29 cm. Very good colors and impressions.  Condition is decent+/good with some wear, soiling, light wormage.  No backing.  Please see and judge from photos. 
 
A man penetrating his lover with his bare back exposed.  Not a shocking scene, but not all that common, just the same.