The Vortex Bunch (ヴォルテックス・バンチ) was a 50-year old secret society led by Kaiser Vortex that was active until they were defeated by the Gremory group, resulting in their disbandment.
The Vortex Bunch was a secret society who were rivals to the Khaos Brigade unbeknownst to Khaos Brigade themselves. The group was founded by Kaiser and his most evil henchmen 50 years ago where in the present day, they knew of the existence of the mythological world as well as the Khaos Brigade's and Qlippoth's activities. Since their inception they had been causing numerous troubles around the world in secret, avoiding the ICPO and when sufficient combatants had been recruited, they had planned to take over all of Japan although the rise of Khaos Brigade foiled their plan. Work of the Khaos Brigade was falsely pinned on the Vortex Bunch, always being accused for their actions. The members consisted of demons, criminals, humans with supernatural powers, and modified monsters and these members dressed head-to-toe in black. The group's catchphrase was to shout "Voooooortex!" while making a V sign with their hands to represent the "V" in "Vortex".
The group planned to take over all of Japan once again, but they were foiled again by the Gremory group during their trip to celebrate Rias' and Akeno's graduation, as well as Issei's promotion to a High-Class Devil. Kaiser, the leader, along with his executives named the Four Invincible Generals were defeated causing the Vortex Bunch to be disbanded with them being handed over to Tobio Ikuse and the Gremory Clan resolving remaining issues.
|Kaiser Vortex||The leader of the Vortex Bunch until its disbandment. He was defeated by Issei and Rias. He is an elderly looking male wearing a helmet resembling a dragon. He is strong enough to fight Issei in his Balance Breaker.|
|Salmon King||A member of the Vortex Bunch until he was killed by Xenovia Quarta and Irina Shidou. He was a salmon head humanoid monster. On his hand was a harpoon and he wore a crown on his head.|
|Count Pentagram||One of the Four Invincible Generals until its disbandment. He was arrested by Japanese authorities. He is a brown skinned man who dresses like a fortune teller, wearing a pentagram on his face.|
|Coach Tiger||One of the Four Invincible Generals until its disbandment. He was defeated by Koneko Toujou and put into a recovery state of 2 months. He is a tiger spirit with a Osaka accent wearing the uniform of the pro-league baseball team Hanshin Tigers.|
|Chief Pork Bone||One of the Four Invincible Generals until its disbandment. He is a pig head monster pig wearing an attire similar to a Ramen shop owner and a towel wrapped on his forehead.|
|Final Death Xiezhi||One of the Four Invincible Generals until its disbandment. He is a black xiezhi the size of a dog. He became Xenovia Quarta's familiar.|
- The name "Vortex" originated from the time when a number of fans mistook the kanji of "Khaos" as "Vortex" and also the fact that sometimes on the internet, their names were misspelled.
- Vortex can be considered a nod to the villainous groups of Tokusatsu, especially that of Showa-era Kamen Rider, such as SHOCKER.
- In the afterword section of Light Novel Volume DX3 - Cross x Crisis, Ishibumi revealed that the Vortex Bunch are strong enough they would have been able to easily defeat the ORC at the beginning of the story.