In Volume 14, Procellarum Phantom was one of the 5 artificial Sacred Gears given to members of the Sitri group that was personally given to Ruruko, which she later used on a mission to save the first-year members of the Occult Research Club that were kidnapped by the Magician Faction of the Khaos Brigade.
Procellarum Phantom has the form of a set of armor primarily on the user's legs.
The armor can strengthen the power and capabilities on the users legs, granting them an increase in combat performance such as greatly enhanced speed and immensely powerful kicks. It can also leave behind after images of the user to confuse their opponents. In True Volume 3, Procellarum Phantom has attained time-based powers that makes time move differently from the user, making the people around users move in slow motion and it makes the users possibly faster than Kiba.
Hyper Procellarum Phantom: The Counter Balance of Procellarum Phantom, which now covers Ruruko's upper body in armor as well. In this form, it greatly increases the user's leg strength and speed, enabling her to jump high and move at a rate that was hard for Issei to track while in his Crimson armor. It also has the ability to deflect and rebound the trajectory of various moves and techniques with a swing of the user's kick
- Procellarum is the Latin word for storms.
- The kanji for the Sacred Gear means "Jade Rabbit and Chang E".