Crystal (クリスタル Kurisutaru) is a rare mechanism that the victim develops once a Drive manifests; it is accepted that the condition occurs in about 1 in 10,000 people for no apparent reason. It gives them various supernatural abilities akin to sorcery.
A Crystal consumes the Magic Element to use the special ability of a Union, Drive. This ability comes at a price, as the soul of the Union becomes polluted and leads to extreme erratic behavior; adding onto this, the Crystal physically becomes a part of the Union, integrating itself with their own nervous system.
The use of Drive is accompanied by a unique sound whenever used, a Discover Call, which can be heard only by the Unions.
Those who become Unions will usually die, due to the mental instability causing them to commit suicide, or their Crystal reaching Phase 6. Children, who received the Crystal, cannot bear its strength and with Drive's usage they die.
Unions existed before the Wadatsumi. They are collectively known as the Irregular Type (イレギュラータイプ Iregyurā Taipu) and the course of their illness differs from the Wadatsumi Unions. There is almost no information about them, and their nunber is unknown.
Another type of Union is Strange Red (ストレンジレッド Sutorenji Reddo). They are Unions who eat other people's Crystals. Usually the absorption of foreign Crystals kills the Unions, but the Strange Reds become stronger, their own Crystal turns red, and they go back to the Phase 0. Unions in Phase 0 no longer progress into the further phases while they continue to eat Crystals. The Enhance (エンハンス Enhansu) is how the absorption process is called, because it strengthens the Union's Drive. During XBlaze – Code: Embryo events it is known there are only three Strange Reds, with one of them being Ripper.
When a person incapable of being a Union received a Crystal, he absorbs too much of the Magic Element, and then occurs Gain Art, which destroys his body, and the Crystal disappears.
During their lifetime as a Union, Unions gradually undergo multiple Phases (フェーズ Fēzu), common symptoms include a change in Magic Element consumption, their Crystal changing color, and a rapid decline in sane mentality. Of all the Phases, Phase 0 is the absolute rarest, with only three of them being known. Unions can jump into the next Phase as time passes on, or as they receive more damage in combat. Conjurers pass through phases slower than ordinary people.
The following are the known Phases:
- Phase 0 (フェーズゼロ Fēzu Zero): Crystal color is red.
- Phase 1 (フェーズワン Fēzu Wan): Crystal color is transparent. Beginning Phase for Unions.
- Phase 2 (フェーズツー Fēzu Tsū): Crystal color is a faint light blue.
- Phase 3 (フェーズスリー Fēzu Surī): Crystal color is blue. Mental stability begins to slip.
- Phase 4 (フェーズフォー Fēzu Fō): Crystal color is dark blue. The ability to tell friend and foe apart is lost.
- Phase 5 (フェーズファイブ Fēzu Faibu): Crystal color is a blueish black. Union will have become fully insane at this point.
- Phase 6 (フェーズシックス Fēzu Shikkusu): Crystal color is black. The Union will dissolve into Magic Element moments into the Phase, leaving behind only their Crystal.
It is believed that Unions in Phase 1-4 can be cured. Unions in Phase 5 and 6 are considered dangerous by the Mitsurugi Agency, and they are eliminated.
A Union can delay going through the phases by not using Drive, giving 3 years before reaching Phase 6.
- Acht (deceased) – Drive: Veil Skin
- Akio Osafune (deceased) – Drive: Iron Shooter
- Akira Kamewari (cured) – Drive: Hekatonkheires
- Artillery – Drive: Unknown
- Gorō Jōizumi – Drive: Screaming Jaw
- Mei Amanohokosaka (in her route only) – Drive: Blood Cain
- Ripper (deceased, Irregular Type) – Drive: Scissor Hands
- Sechs (deceased) – Drive: Deadly Sign
- Tōya Kagari (Irregular Type) – Drive: Unknown (controls blood)