Stand still is the unofficial name for an unknown disease that causes a mental and physical comatose state.
Overview
The disease has no official name, and is only called a stand still by Kei. The disease has no official cause, but seems to happen when a subject undergoes emotional stress. It has several key symptoms before happening to a subject.
Symptoms and cause
When ever it happens to a person after the initial stand still, will suffer from a detachment from a situation. They will move slowly and continue to slow down until the subject enters a comatose hibernation. During this their breathing is faint, and barely noticeable without careful observation. Kei believes that stand stills happen when a person can no longer tolerate the world around them, and chooses to "depart reality". It also somehow able to stop a person's cellular mitosis thus prevents them from aging, as revealed by Kei and Ichigo who are chronically 18 and 23 but look 15 and 12 respectfully.