Celestial spirit magic is the use of gate keys to summon celestial spirits for aid, be it combat or not. The Gate keys themselves are used to open a gate for the celestial spirit to pass through. There are 2 types of key classes, Gold, the more rare keys, and silver, the more common keys. Every key a caster acquires is measured as a unit. The caster is noted by how many units they obtain.
Contracts and RulesEdit
When a caster opens a keys gate for the first time the caster must set up a contract with the spirit to which the key belongs, this contract pretains to which days the spirit can be summoned. This contract forms a very serious bond with the caster and the spirit. However, under the circumstances the spirit is being summoned for the first time, and the spirit's aid is greatly required, the contract can be suspended to be arranged on a later date. Contracts between a caster and a spirit can be broken if the caster is arrested, sets the spirit free of its contract, or dies. When a spirit is summoned it appears next to the caster who summoned it, it is impossible to summon a spirit anywhere else. There are also certain rules that the spirit must obey that are set by the Celestial Spirit King, so far the only rule introduced is that a spirit may not directly or indirectly kill its caster. When a gate is closed it is mandatory that both the caster and the spirit agree on the gates closure, however there are certain casters strong enough to will the spirit back into the celestial world. The contract set by the caster and spirit is not limited to the days they are summonable, they may also agree upon the spirits own summonable will, where the spirit summons itself. At anytime the caster may dissolve the contract, some very strong spirits such as Leo, can will themselves into the human world, and stay there for as long as their strength permits.
Ophiuchus, The snake charmer, has little history known about him, other than that he has a contract with Yukino Aguria