瑠璃斎胴
What is Lapis Lazuli Room Armor (Rurisai dou)
of Samurai Armor

This refers to a type of chest armor (Do) where the upper central part of the front torso can be detached. It is said to have been designed to allow the wearer to reach into the pocket of their kimono while still wearing the armor. It is named after a military scholar named Gen’emon Rurisai, who proposed this design during the Kan’ei era in the early Edo period.

See more terms related to samurai armor in this samurai armor glossary

Samurai armor parts explained

Samurai armor history and types