One of the heads of the Principality of Zeon, Gihren is the oldest son of Degwin Sodo Zabi, the ruler of Zeon and the instigator of the war with Earth. With the death of Degwin's favorite son Garma Zabi in battle, Degwin withdraws from day to day duties as Zeon's leader which effectively made Gihren the leader of Zeon. This was most evident in the speech Gihren gave at Garma's state funeral. This speech was notable for possibly being the debut of the trademark salute "Sieg Zeon!" (literally translated as "Victorious Zeon"). Giren was gifted with a high IQ (240) and ingenious oratory abilities. He and his sister Kycilia were constantly at odds with each other as both had similar political goals but different methods.
Although Gihren was successful in reducing his father's role to that of a figurehead ruler, he must still endure Degwin's critisicms and scorn. Degwin saw Gihren as little more than an updated version of historical dictator Adolf Hitler (a role that Gihren was all too happy to take to heart.)
Gihren's own father compared him to Hitler, which may not be completely inaccurate. Like Hitler, Gihren appeared to believe in a "survival of the fittest" mentality and that the "Superior Race" should rule over the inferior ones (the superior race being Spacenoids from Side 3 and the inferior the Earthnoids). He also shared Hitler's gift for oratory and manipulation, taking the reins of power from his father behind the scenes the way Hitler did with the German president of his day.
Unluckily for Gihren, he also had a number of Hitler's personality flaws, such as an over-reliance on miracle weapons to turn the tide against numerically superior foes. By this logic, the assorted super weapons such as the MA-08 Big Zam and Apsalus Project Mobile Armors can be seen as analogies of the V1 and V2 rocket-bombs used by the Third Reich. Like Hitler, he also greatly overestimated the capability of his forces. This was shown during the final battle of the One Year War, when despite his claims of superiority his forces were overcome by those of the Federation.
In an effort to circumvent the Antarctic treaty (forbidding nuclear, biological, and chemical weapons and colony drops on Earth), Gihren's most ambitious project was the Solar Ray cannon. This consisted of a hollowed-out colony cylinder rebuilt into a giant carbon dioxide laser with the ability to destroy entire fleets. Gihren learned that Degwin, tired of the war, decided to take his personal fleet to a designated area in space where he would meet the fleet of Earth Federation representative General Revill and discuss peace negotiations. Gihren arranged for an accidental firing of the Solar Ray which destroyed Degwin and Revill's entire fleet. However, this may have cost Gihren one of his tactical advantages, as the premature firing burned the laser out.
Kycilia, eventually learning that the death of her father was no mere accident, personally executes Gihren for the crime of patricide. As a result, she takes over during Battle of A Baoa Qu. This resulted in many Gihren loyalists withdrawing from the battlefield.