The Gekka (月下?, lit. Moonlight) is a Knightmare Frame model based on the Guren Mk-II. Using the same motorcycle seat design, it boasts sixth to seventh generation technology, making them superior to Britannia's fifth generation mass production models, the Sutherland and Gloucester. The only units seen are used by the Four Holy Swords and their leader, Tohdoh. They switch to the Akatsuki variants following the destruction of their Gekkas during the failed attempt to kidnap Nunnally vi Britannia and the Black Knights' subsequent exile from Japan in the second season.
The standard Gekka, sometimes referred to as the Shiseiken version,[41] differs from the Guren Mk-II in several ways. It has silver armor as opposed to red (Kōsetsu Urabe briefly pilots a light blue model), and the head unit is replaced with a monoptic model. It doesn't possess a radiant wave surger, either, and the cannon embedded in the left arm has been replaced by a fully automatic rifle. Its primary weapon is the Katen Yaibatou, a heated chain-sword which can shear through Knightmares with ease. The Gekkas are equipped with a "Chaffsmoke" dispenser which enables dispensing of both chaff and a smokescreen, which negates both visual tracking and electronic equipment.
Kyoshiro Tohdoh's Gekka is customized with two hair-like appendages flowing from the back of the head. His variant sports a black paint scheme and a unique version of the Katen Yaibatou dubbed Seidoutou (制動刀, lit. "Brake Sword"?). The Seidoutou has a Slash Harken mounted on the butt of the handle as well as several thrusters on the back of the blade, which can either increase the blade's force when swung or allow for a quick retreat by using it for an extra boost of speed. Tohdoh pilots a regular Gekka early in the second season, his custom unit having presumably been destroyed or captured along with him during the Black Rebellion in the first season.
In Code Geass: Lost Colors, the protagonist Rai receives a prototype version of the Gekka if the player chooses the Order of the Black Knights route. Called the "Gekka Pre-Production Test Type", this prototype unit is two-tone blue rather than gray, and is more akin to the Guren than the actual Gekka, possessing a three-fingered prototype version of the radiant wave surger, though mounted on the left arm rather than the right. In the second season, the Guren mounts a nearly identical arm as a replacement for its original one destroyed in the finale of the first season
