They are the remains of three Futasugi magical girl gangs: The Ryuugasaki (竜ケ崎 Ryūgasaki) faction, The Torayamachi (虎屋町 Torayamachi) faction and finally, The Janomiya (蛇の宮 Janomiya) faction. Because of the Wings of Magius's work, there was a severe drought of Witches in areas outside of Kamihama, which ultimately led to a very bloody civil war in Futatsugi between the three gangs. After months of fighting and dozens of deaths, they learned that the Magius had caused their Witch drought and united on the basis of vengeance. Their goal in Arc 2 is to steal Kamihama’s Automatic Purification System as revenge for the Magius stealing their witches and causing so many deaths.
As of Arc 2 Chapter 7, they finally put an end to the conflict with the Union.
The original leaders of the three factions of Futatsugi City. They united as one group and serve as the leaders of Promised Blood:
- Yuna Kureha (former leader of the Torayamachi faction)
- Ao Kasane (former leader of the Janomiya faction; Temporary Undercover in the Ryuugasaki faction during the Futatsugi civil war)
- Juri Oba (former leader of the Ryuugasaki faction)
Hikaru Kirari, while not a leader, acts as a direct subordinate of the three.
Several Magical Girls have been sent in to infiltrate and investigate Kamihama, in an aim to learn more about the purification system that's in place:
- Ranka Chizu (former member of the Ryuugasaki faction)
- Sakuya Suzuka (former member of the Torayamachi faction; deceased)
Other known members of Promised Blood that operate in other capacities.
- Ulala Yume (undercover member of Folklore of Zero)
- Hikaru Kirari (also known as 'The Horse'; Torayamachi member temporarily undercover in the Janomiya faction during the Blood Tragedy)
Futatsugi City Magical Girls
The lowest ranking members of the group. Nameless magical girls only identified by rank, they are the ones wearing hoodies or vests and a face mask sometimes adorned with spray-painted fangs.
- The names of the former factions refer to animals. In particular, Ryuugasaki and Torayamachi refer to the duality between dragon and tiger, respectively, while Janomiya refers to a snake. It should be noted that Ryuugasaki and Torayamachi in particular were bound in a rivalry.
- Yuna, Juri and Ao forming a sisterhood is likely referencing the Oath of the Peach Garden in the historical novel about Three Kingdoms in China.
- In the Oath of the Peach Garden, Liu Bei, Guan Yu and Zhang Fei became sworn brothers although they are not related by blood.
- This ceremony later evolved over time in the mafia world, as during the similar ceremony, the participants cut their fingers, let blood flowed out and mixed into their drink, then drink them together, as if their blood has blended together to make them siblings.
- This is basically what Yuna, Juri and Ao did at the end of Crimson Resolve, hence the name: Promised Blood. But in their case, they cut their wrists instead of their fingers.
- In the middle part of their logo, there is a spiked club, or a Kanabo, which is Yuna's weapon.
- The Promised Blood were a structured and hierarchical group with the three sisters - First-born Sister(長女, Chōjo), Second-born Sister(次女, Jijo) , Third-born Sister(三女, Sanjo) (boss, regarded as a surrogate Big Sister) at the top and Younger Sister(妹, imouto) (subordinate gang members, regarded as a surrogate Younger Sister) at the bottom. This hierarchy resembles a structure similar to the family – like a Yakuza's hierarchy structure(oyabun-kobun relationship).
- During the battle between Torayamachi and Ryuugasaki on Monzenbashi Bridge, each faction is shown to have 18 members (plus 2 in Ryuugasaki and 1 in Torayamachi who did not participate in the battle). As 11 more girls died before the formation of Promised Blood, it can be assumed Promised Blood has about 28 members (not including Ulala).