Second half 18th century
 
The entire ground is a geometric pattern of inlaid pearlshell, inlaid with an inscribed trompe-l’œil lacquer ink cake with inscription including a “signature” Ritsuo with kan seal on one side, a lacquer brush and bone seal carved with a peach on the other. The risers of the red lacquer interiors are decorated with chinkinbori waves. With a coral ojime. 
 
L. 7.5 cm
 
The inro itself appears to be a superior example of a type that originated in the Ryukyu Islands (modern day Okinawa) and was adopted or their cord runners by the Somada school of lacquerers.  But it appears to have been ordered, or adopted, by a sophisticated follower of Ritsuo. The clue may be in the decoration to the risers, typical of the work of Nomura Chōhei.

The text on the ink cake reads:
“磾｝珋磾籩変｝剢湞磪憟｛ㄗ珋磾籩雰｝剢湞磪憟ㄘ｝堞頨謾｝観
„Kyoho go kanoe-ne, „Kunshi wa hyohen su, sono bun utsu taru nari“, Ritsuo sei, with the seal Kan“
 
[Kyoho 5th year in the year of Kanoe-ne (1720), „Gentlemen change like leopards, the glory shines more and his writing is also wise“, made by Ritsuo, with the seal Kan].