Sometime before the First Modern War, the Rebel Army required an affordable tank that would have a good range of mission profile, with balance between firepower, mobility and survivability. They already knew that what was left of the Regular Army was already producing and amassing a fleet of their own SV-001s, and Girida-O was meant to be its direct opposition. Even though classified as an MBT, Girida-O fills the role of a medium tank, complementing heavier tanks still in service such as Di-Cokka or Iron Iso. Girida-O sacrifices protection in favour of a smaller frame and faster speed. Due to design flaws, tank operators often ran over their own infantry support. In the course of the Modern Wars, the tank has seen a number of improvements.
Girida-O's chassis is utilised by the Rebel Army for other purposes, such as material transportation and bulldozing. A utility variant with the turret removed and equipped with a front bulldozer blade and a hydraulic dumper named Dararin Dara Dara is the primary transport of materials of the Rebel Army.
Other factions later involved in Girida-O's production are the Amadeus Syndicate and the Ptolemaic Army. The latter faction based on data stolen from the Rebel Army has developed its own variant (Ver. P.M.)  with improvements over the original, such as better armour protection without sacrificing mobility, as well as a superior cannon with an improved loading mechanism and higher stopping power. Additionally, the problem of situational awareness of the crew (that had plagued the original model) has been fixed, reducing infantry accidents to a minimum. The resulting AFV is also more expensive to manufacture.
The Girida-O is a tricky tank to defeat, due to its cannon shells flying in an arc and its speed. One of the few ways to fight it is to go very close to it and crouch, then continuously shooting at it. However, there is a risk of being ran over by the tank. Another way is to stay out of its line of sight and shoot it from afar. Using grenades is recommended.
|Girida-O: The original, most common variant.|
|Girida-O MKII A gray variation of the Girida-O. This variant first appeared in Metal Slug on the back of the Iron Nokana. It is specifically customized to protect VIP escort vehicles.|
|Girida-O (Anthology): A gray variation with red stripes of the Girida-O. Only appears in the menu of Metal Slug Anthology.|
|Girida-O (Universal): A weak gray variation of the Girida-O that only appears in Universal Metal Slug.|
|Girida-O "Dararin Dara Dara": A utility variant that can dump I-beams onto players.|
|Girida-O Ver. P.M.: a Ptolemaic variant that is faster and better armored.|
|Future Girida-O: an improved variant that is faster and better armored. It fires magnetic shots that can pierce through weak rocks and can make the latter crush the player near them.|
|Girida-O P.M+: A purple version of the Ptolemaic Girida-O that is faster and better armored than the original version, capable of ramming enemies at high speeds. Appears in Metal Slug Attack.|
|Girida-O P.M Ver. Expidition: An enhanced version of the Girida-O P.M+ deployed from the Land Blowfish. Appears in Metal Slug Attack.|
- Girida-O's design is somewhat similar to a M24 Chaffe, with some little modifications on the Hull.
- (Found in Metal Slug 6 standalone, not in anthology) An early concept image depicts Girida-O with a mine plough and a machine gun on top of the turret. Its treads are similar to the Di-Cokka's.
- The early concept depicted at the right resembles a M4A3 Sherman Jumbo with frontal track skirts, though it looks plump.
- Single-shot Grenade launchers are mounted on Girida-O's turret, however those are never used on-screen.
- This tank is currently the only one whose chassis had been re-purposed for utility.
- Its treads in the game are the same ones the SV-001 (Metal Slug) uses.
- The original Girida-O's cannon goes back from recoil when it fires. However, the Ptolemaic variant's cannon goes forward instead when it fires, giving it a little more range.
- A Girida-O also makes an appearance in a cutscene of Metal Slug 3D with Allen commanding it during an assault at a Regular Army base where it and several Di-Cokka's fire shells towards Eri and Fio, killing both of them.
- The Ptolemaic Girida-O appears as a loading screen of Metal Slug XX.
- Metal Slug Attack unit description File:MSA_Screenshot_unit_Girida-O.png
- Metal Slug Anthology (Wii) Introduction Manual, p.9 - Game Overview: Metal Slug
- Metal Slug Attack unit Stats
- Metal Slug Attack unit description File:MSA_Screenshot_unit_Girida-O_Ver._P.M..png
- Metal Slug Attack unit Stats
- Metal Slug Attack unit description