Japanese for "maiden circuit" ("otome" means "maiden" or "virgin", "kairo" means "circuit"). In the anime series Saber Marionette J, the otome kairo are special devices in the marionettes Lime, Cherry and Bloodberry. The circuits give them emotions and personality. Each of the three circuits is different, and represents a different quality supposedly possessed by Lorelei. Lime's embodies innocence, Cherry's virtue, and Bloodberry's motherhood. Together, they may have the power to save the world....

There are four other marionettes with otome kairo in the SMJ universe. The three Saber Dolls also have them, and correspond to the three Saber Marionettes. Tiger pairs with Lime, Luchs (aka Lynx) with Cherry, and Panther with Bloodberry. The last one, Marine, is found in the SMJ OAVs, and exactly how she ended up with an otome kairo is a major plot point in the OAVs.