Arena leagues have long offered a home to the castoff machines of Great House armies, BattleMechs deemed no longer fit for combat. Demilitarized and dropped into a BattleMech boneyard or sold for scrap, quite a few of these find their way to Solaris, bought for parts or refurbishing. Through this practice, the Koto first saw the light of day.
         In early 3050, OmniTech Industries sought to develop a new 'Mech that could be competitive in the Class Two arenas. With a seemingly unlimited supply of scrapped Locusts available, the company's engineers based their prototype on that ubiquitous light BattleMech. Many of those Kotos were built and did well, but OmniTech never did work out all the bugs involved in making the Locust chassis carry so much weight.
         Until they found a junked Locust IIC. They instantly realized that its heavier chassis could easily handle the weight load and went to work on it. The Locust IIC had been badly damaged, its cockpit beyond repair, so they grafted the head of a Jenner to it and added a new set of weapons. The hybrid worked well in tests and in 3052, they debuted the Koto design to great acclaim from the fans and the MechWarriors.
         Rosa Kisareg helped make them a household name in the Class Two arenas of the 3050s, until she left for the mercenary life. Mercury Sdeidt took her place into the 3060s, keeping sales high with performances of her "Quicksilver" grace and destruction until the Jihad began.
         During the Jihad, OmniTech-affiliated "garage" factories kept building Kotos as long as possible, until Word hunter-killer teams destroyed them all. But thanks to the return of Rosa Kisareg and Mercury Sdeidt to combat, the Kotos never stopped fighting. The Word learned to fear the arrival of the Kotos, and when the Solarians finally drove them off world, they continued to field the handful of Kotos that could still fight.
         In 3080, after years of rebuilding amidst the shattered streets of Solaris, OmniTech unveiled a rebuilt factory and the Koto that still stands to this day.

         OmniTech’s designers believed that the MechWarrior who successfully landed the first blow was most likely to win the bout. To give ’Mech pilots that capability, they tried a number of different weapons and ultimately chose a laser array built to maximize punishment. Earlier versions also sported machine guns, a deadly weapon in the arenas, or against the Word infantry they gained a reputation for slaughtering.
         The current version of the Koto though is the one most identified with Solaris of today. While lacking jump jets and hands that many other light BattleMechs have, the Koto is fast enough to outrun most other 'Mechs in the city or on the field. Basing the head design on that of the Jenner also made it a more comfortable BattleMech to pilot, with a larger cockpit area for the MechWarrior to reside in. This makes it possible for Koto MechWarriors to stay on station for days. Heavy Rock Hard Mark II Ferro-Fibrous also protects the Koto far better than any Locust ever made, making it capable of remaining in battle for far longer.
         The current Koto's main armament consists of twin Farstar lasers on the shoulder turrets, one large Pinpricker laser slung under the head, and a small Pinpricker jutting out over the cockpit. The first three weapons make it deadly to enemy BattleMechs, while the last weapon has proven dangerous to infantry caught in the open. Of course, many MechWarriors never bother to fire the small laser at enemy troops, preferring to charge into their midst, come to a sliding stop through them, and shake or paw whatever remains of the infantry off their feet. Infantry often break at the mere sound of the Koto's distinctive Shipil AeroSpace engine spooling up to full power before the charge and MechWarriors have learned to use that reaction to their advantage whenever possible.

         The modern Koto is the primary light BattleMech of the Solaris Irregulars, and a favorite of the DropShip Irregulars as well. OmniTech also makes a practice of selling them to other mercenaries in the Allied Mercenary Command, which sees them deployed throughout the Human Sphere.