Calming Water

The Calming Water (水憩う, Mizuikō) is a unique liquid that carries special and magical properties. It is kept in Reiōkyū.

Overview
Said to be a tool of the Kami themselves, the Calming Water is said to carry special properties which act to bestow a trial upon the one who drinks the water. It stimulates and manipulates the key emotions within their mind and soul which are the most prominent at the moment of consumption, empowering the drinker through this process. Because of this aspect of the water, it was said only those who have a strong conviction would be able to survive the trial of drinking it.

The Calming Water works by acting upon the emotions that are most strong within the individual who drinks the liquid. By doing so, the water magnifies these emotions to almost extraordinary proportions and literally drives a person beyond what they can normally handle. What actually happens is that it transforms these emotions temporarily into an extremely potent and fatal poison-like substance that attempts to destroy the soul, body, and mind of the consumer. While what the drinker must actually do during the trial is expressively unknown, as it appears to vary between individuals and what emotions the water acts upon (it has been likened to the internal confrontation between one's Inner Hollow during the attempt at mastering Hollowfication), the result of passing or failing is normally always the same; death awaits all who are unable to pass the water's trial. However, as the drinker strives to regain control and to maintain themselves during the painful trial, or as one might say, should the water "accept" them, the pain within begins to subside and a powerful calming effect spreads throughout the body; hence its name, "Calming Water". Kirio Hikifune commented that many who attempted to drink the water had met their end because they lacked the drive and indomitable spirit to overcome the trial. In other words, for one to truly succeed in the water's trial, they must bear a strong motivation and willpower that exceeds all common expectation. The emotions magnified so strongly and turned into poison that should have, by all supposed accounts, ended their lives, become pure power as the drinker is strengthened in all aspects exponentially. One feels at peace with their world and becomes capable of sensing energy on a level far beyond what anyone might be able to attain through commonplace training (although for one that has achieved abnormal levels of skill, such as a Grandmaster of a specific combat field, this may not apply). Although by how much one's power is increased from drinking the water, it is said to be significant enough to cause the drinker to almost transcend their previous precipice of power. It is noted, however, that the strength of the emotions the water acted upon is the key determining factor that will decide just how far the drinker's power advances. One that abandons emotion while retaining a strong heart would find themselves to grow no stronger from drinking the water, as the liquid would have nothing to act upon. Many Royal Guardsmen were said to have lacked any real drive to gain strength but were strong-hearted, meaning they could survive the water's trial but found themselves to have rose very minimal in power level.

Final Test of the Royal Guard
It is the final test that the King of Souls puts one through that will allow for a promoted Shinigami to be accepted into the Royal Guard. If they fail to pass, the water's poison-like properties will kill the one who drunk the liquid. Quite obviously, this means that the Kami themselves have refused to accept that person as a warrior of the heavens. Kisuke Urahara, during his tenure as Captain and his eventual visit to the Royal Palace, had learned of the liquid's existence and had once attempted to replicate its effects through the mixture of several substances using a liquefied Hōgyoku as the base.

Known Drinkers

 * All Members of the Royal Guard

Behind the Scenes
This was based off of the Ultra Divine Water from the anime and manga series, Dragon Ball.