Gui Xian (龜仙) in some of the official English versions is a misnomer because "Gui" belongs to a different concept of the Chinese four benevolent animals (Si Ling or Ssu-Ling).
"One of the Ssu-Ling, celestial creatures in Chinese lore. It represents the direction north, the season of winter, and the element of water."
—Devil Summoner: Soul Hackers 3DS Compendium
Persona 3
"One of the Ssu-Ling, celestial creatures in Chinese myth. It represents the direction north, the season of winter, and the element of water."
—Persona 3 Compendium
Persona 4 The Animation
In Persona 4 The Animation, Genbu is the Persona that represents the bond between Yu and Eri Minami.
In the True Ending Special, Genbu appears to defend Yu from Margaret's Loki and its attacks, as well as bring a message of support for Yu from Eri.
Digital Devil Saga: Avatar Tuner
After defeating Ananta in the final floors of the Karma Temple, the Embryon can come down from the tower and find out four powerful demons have taken over several sectors of the Junkyard. Gui Xian appears in Anahata. The Asura Gui Xian is a woman who follows the orders of Huang Long. The battle is quite simple as long as Gui Xian is not hit by Earth spells, either the Embryon's or her own, as they will greatly heal her. Curiously, Genbu's two heads keep on bickering through the battle.
Gui Xian gets three turns per round and the fight is typically played out in three stages. In the initial stage Gui Xian will only use light damaging skills. After more bickering, the second stage will begin and they will instead begin casting Magic Repel every round and switch to mid-tier attacks. After trying to let the party off with a 'warning', the party will appear to insist to keep fighting and Gui Xian will not seem too enthused; this begins the final stage. Gui Xian will keep throwing up Magic Repel and switch to heavy damage attacks in addition to using Rage for extra turns.
One problem faced when fighting Gui Xian comes from their extremely high resistance to Physical and Gun attacks, almost nulling them completely. Once the second stage starts and Magic Repel comes into play it becomes difficult to damage them without access to some form of Almighty-based attack. However, if the party casts so much as a single -kaja skill, Gui Xian will start another conversation in which they accuse the party of taking cheap shots. Casting a -kaja skill every round with the character with the weakest magic stat will allow for two magic damage dealers to keep attacking, since Gui Xian will use Dekaja instead of Magic Repel every time.
Devil Survivor 2
"One of the Ssu-Ling, celestial creatures in Chinese lore. It represents the direction north, the season of winter, and the element of water."
