|Previous Affiliation||Gotei 13, Soul Society|
|Position||Commander of Aizen's Army|
|Previous Position||Captain of the 3rd Division|
Lieutenant of the 5th Division
3rd Seat of the 5th Division
|Previous Division||3rd Division|
|Partner||Sosuke Aizen, Kaname Tosen|
|Previous Partner||Izuru Kira|
|Base of Operations||Las Noches|
|Bankai||Kamishini no Yari|
Gin keeps his eyes constantly narrowed to slits, rarely ever opening his eyes enough to reveal their bright sky blue-color. He is unusually thin and tall with very sharp features, giving him a skeletal appearance. He bears unusual silver hair. He also keeps his face set in a wide mocking smile, which he only wipes off on rare occasions of annoyance, surprise, confusion, or even sadness.
In Hueco Mundo, his outfit, like Aizen and Tosen's, has been modified since the three abandoned Soul Society. He now wears a long, white robe over his normal Shinigami hakama. The hilt of his Zanpakuto is visible sticking out from under the robe through the opening down to his waist. Later, Gin is seen wearing a white hakama like the Arrancar, instead of the black ones he was last seen in. Gin wears his robe open in a narrow 'V' down to his waist, closed to below the hips, and then open again to the hem, which falls about to mid-calf. His robe has long bell sleeves, into which he hides his hands like some do with kimono sleeves. The lining of the robe and edges or layers of the under-robe(s) appear to be black. From other examples, it is likely he is also wearing black tabi with white waraji. His Zanpakuto is not visible with this outfit.
Gin is enigmatic and mysterious, since his almost constant smile and slitted eyes, combined with his heavy use of sarcasm and mocking politeness, make it very difficult to discern his thoughts. Many find his demeanor and appearance rather unsettling and there are very few who were willing to trust him even before he was revealed as a traitor. Gin seems to be fully aware of the effect he has on others and more than once has been seen toying with people's emotional states for his own amusement. Gin's speech tone is polite and indirect. He can also be rather mischievous, and other times, he can be quite sadistic.
Gin grew up in the outer districts of the Rukongai, which was a living hell. He eventually encountered a starving Rangiku Matsumoto and gave her a dried persimmon, which would become their mutually favorite food. The two became companions, with Rangiku even deciding that the day they met (September 29) would be the day she celebrated her birthday. Later, while Gin was firewood, he spotted Aizen and three of his subordinates, with the villainous Shinigami carrying a ball of pink energy that he inserted into a prototype Hogyoku. Realizing that the energy was Rangiku's and that Aizen was responsible for what had happened to her, Gin vowed that he would kill Aizen one day.
Over a century later, Gin graduated from Shin'o Academy after just one year, and was given a seated position in the 5th Division. One night, Aizen found Gin after the latter had killed the 3rd Seat of the 5th Division. Aizen praised Gin's efforts and asked his opinion of the 3rd Seat, to which Gin replied that the 3rd Seat was worthless. Aizen immediately gave Gin the now vacant 3rd seat of the 5th Division and covered up the fact that Gin had killed the 3rd Seat.
Gin would assist Aizen in many of his schemes, gaining his trust to the point of being entrusted with the secret of the power of Aizen's Zanpakuto, Kyoka Suigetsu. Among these schemes were the Hollowfication of eight Shinigami who would later become the Vizards and the framing of Kisuke Urahara for the crime. He later became the captain of the 3rd Division through Aizen's manipulations, with Izuru Kira as his lieutenant.
When Ichigo Kurosaki invaded the Soul Society with his friends to rescue a condemnded Rukia Kuchiki, Gin gradually revealed himself as a traitor, which did not surprise anyone due to his behavior, and escaped to Las Noches with Aizen and Kaname Tosen (the captain of the 9th Division) after a somewhat tense confrontation with Rangiku.