The technique Rain was developing utilized the body's natural response to stress or danger also known as adrenaline. Adrenaline is a hormone that triggers the body's "fight or flight" response, providing a surge of energy and strength in times of stress or urgency. It increases heart rate, boosts blood flow to muscles, heightens awareness, and temporarily enhances physical abilities.
Rain aimed to harness this innate response intentionally, seeking to create situations that could trigger the release of adrenaline at will. By designing combat scenarios or techniques that induced stress or urgency, he intended to prompt the body to produce this hormone, thus granting him heightened physical capabilities when needed.
