Trinity Seven

 is a group of seven female mages that mastered their respective Archives of magic, destined to meet the Demon Lord and influence the fate of their world.

Background
In every reality, seven female mages that have mastered each one of the Archives of magic gather to form the group Trinity Seven before encountering the Demon Lord. Although, the relationship between the Lord and Seven can differ between each universe, such as elimination, domination or recruitment, their meeting will always begin the destruction of the world and creation of another afterwards.

Requirements
Originally, it was stated that in order to become a Trinity Seven, one must master the Lost Techniqa or Last Crest, the ultimate spell of an Archive developed by the founder to possess immense power but with costly consequences. Later, Hijiri stated that mastering three Thema from a single Archive would also qualify one for reaching 'Trinity.'

Originally, the seven greatest mages used their Last Crest to defeat the true Demon Lord and seal his soul into the farthest part of the world. Afterwards, concerned over the overwhelming strength of the spell, the founders decided that only one mage should be able to use each of the Crest, thus establishing the system of the Trinity Seven. As a result, no one other than the Seven can understand the spell regardless of the amount of research.

Unfortunately, since only a single individual can wield the Last Crest, only one Trinity Seven of each of each Archive can exist in a world. Thus, if the equilibrium is broken, the original will be removed from existence in order to maintain the balance of the system. However, methods to circumvent the requirement exists, but only receiving magic from a Demon Lord Factor has been proven to successfully maintain subsistence.

Trivia
 In the first popularity poll, the Trinity Seven, including former and alternate members, ranked in the following order:  