The Tamer Union is an organization of Tamers who work to maintain order in the Digital World. The organization was founded by DATS, but it's not considered a legitimate organization by Gaia Origin (the self-proclamed "Guardians of the Digital World"). After Koh/Sayo defeated Gaia Origin in battle, the organization is finally recognized as legitimate by them.
In Digimon Story, Tamer Union works on solving quests for Digimon. Humans are trained and supervised by the Four Holy Beasts, while Digimon are trained by Clavis Angemon. At one point in the story, the Player faces Chronomon to prove the value of the Union to Alphamon.
Tamers are classified by ranks, each of the Four Holy Beasts (along with Clavis Angemon) is responsible for each type of Tamer:
- Qinglongmon -> Normal Tamers
- Xuanwumon -> Bronze Tamers
- Baihumon -> Silver Tamers
- Zhuqiaomon -> Gold Tamers
- Clavis Angemon -> Platinum Tamers
After the events of Digimon Story, Tamer Union was divided into Light Fang and Night Claw, inhabiting the two halves of an island: Shine City and Dark Moon City, respectively. Both often fought each other in tournaments until a mysterious digital life-form began to wreak destruction in Shine and Dark Moon City. Shine City is overseen by Ofanimon and Chief Glare, while Dark Moon City is overseen by Chaos Dukemon and Chief Julia.
The last quest in the game involves a challenge promoted by Gaia Origin, the self-proclaimed Guardians of the Digital World. They don't recognize Tamer Union as an official organization until they are defeated by Koh/Sayo, when they decide to recognize the Union officially.
It's also revealed that Ofanimon and Chaos Dukemon were members of Gaia Origin who left the group to lead the Tamer Union.
Tamer Union is mentioned as a destroyed organization.
Some old members of Tamer Union appear in the coliseum.
Tamer Union is mentioned by Mikagura Mirei and Sayo.