With the moon being largely on a defensive footing, there isn't much of a need for a fast-attack Axel that typically fills the light axel role. Any strike or interception duties are largely fulfilled by the OUS-10, a hybrid fighter-ground combat Axel. Nevertheless, the Lunar forces do have one Light Axel unit in their inventory, which is the Mihimi.
Origins of the OUL-12 are unclear- ranging from being a cheaper alternative to the OU-8 to an out-of-control study on what a Light Axel produced with Lunar Technology could make. Whatever the origins, the result was a small production run of OUL-12 units that were distributed across the moon. One factory plant continues to produce these units and the spare parts needed to maintain them.
The OUL-12 is something of an oddity, since the OU-8 Already performs all the duties that the OUL-12 is supposed to fill. The Mihimi is lighter than its Krigga counterpart, and saves on weight and speed requirements, but cannot hold medium axel armaments and has difficulty operating with the armament harnesses that the OU-8 and OUS-10 use to augment their firepower. Operationally these units see long-term patrols and postings at remote outposts, even though they are largely outnumbered by the OU-8.
As an aside, weapons produced to fit the OUL-12 have mostly gone to OUS-10 squadrons, as the manipulators between both units are largly the same size, and OUS-10 pilots feel that the added directorial firepower is worth it instead of relying on the weapons harnesses alone.