Kiryu, also known as Mechagodzilla 3, is a kaiju-sized mecha designed by the Japan Self-Defence Forces. Interestingly, this incarnation of Mechagodzilla is more of a cyborg, as opposed to a straight-up robot, since it was built around the skeleton of the original Godzilla, killed in 1954.
When a second Godzilla appeared in 1999, the JSDF, in desperation since their maser weapons didn't work on Godzilla, dredged up the skeleton of the first Godzilla from Tokyo bay and commissioned a robot to be built around the bones. In 2003, Kiryu was completed and almost immediately deployed into battle against Godzilla. The battle was brief, since after a few hits from Kiryu, Godzilla departed for the ocean. His roar, however, awakened Kiryu's soul in the DNA fragments within his skeleton. Remembering his attack as the first Godzilla and subsequent death, Kiryu went on a rampage, destroying more of the city than Godzilla did, until his power ran down, as control of him could not be regained. After some more work was performed upon the cyborg, he was sent back into battle a short time later when Godzilla returned. The two monsters appeared to be even in sheer strength, and Godzilla was only driven away after Kiryu's thrusters propelled both him and Godzilla out to sea before the cyborg's Absolute Zero cannon could be fired. The battle left Godzilla with a huge gash in his chest, and Kiryu heavily damaged with one arm and the Absolute Zero cannon destroyed. While Kiryu was being repaired, his Absolute Zero cannon replaced with a Tri-Maser, the Shobijin, Mothra's twin fairies revealed that Godzilla only kept returning to Japan because his predecessor's skeleton resided within Kiryu, a violation of the natural order. If the skeleton was returned to the sea, Mothra would take Kiryu's place in defending Japan. If not, Mothra would declare war on humanity. Later, Kiryu was drawn into battle against Godzilla and Mothra, but was brought down. His missing right arm was replaced with a drill and he soon battled Godzilla again, opening the wound in his chest before the now deceased Mothra's twin larvae bound Godzilla in web. Kiryu's soul was reawakened by Godzilla's roar again, but this time, Kiryu grabbed Godzilla, secured them together with cables, and carried Godzilla to the bottom of the sea, never to be seen again.
As a Mechagodzilla, Kiryu is well equipped to tackle Godzilla. He is equipped with a maser cannon in his mouth, mimicking his old atomic breath, detachable dual laser cannons on each arm, and a flight pack containing two rocket launchers and missile batteries on its back and sides. This flight pack can also be detached at launched at the enemy before being remotely detonated. In close-combat situations, Kiryu can retract a blade from his arm cannons, which can cut through Godzilla's hide and administer small electric shocks. Unlike its predecessors, Kiryu can actually move his tail giving him one more advantage in combat, but his most devastating weapon is the Absolute Zero cannon within his chest, capable of instantly freezing its target, leaving it to collapse under its own weight.
His greatest asset and design flaw come in the form of the DNA computers manning it. The DNA computers, which use DNA from the Godzilla skeleton within, enable him to move fluidly with an almost organic quality, but this can backfire, as Kiryu can act on his own accord, taking actions unauthorised by his remote operators, as evidenced by his rampage following his first battle, and how he ultimately dealt with the new Godzilla.