Fūjin

"Usually, only someone compatible with a black trigger can use it. But Jin's Black Trigger... Wasn't particularly picky."

- Shiori Usami about Fūjin

The  is a Black Trigger created by Sōichi Mogami.

Description
The Fūjin's overall appearance when deactivated is a long, black sword handle with green circular designs on the bottom half of the handle and a green line in the middle of those designs. When activated, it releases a blade of green energy, similar in appearance to a Kogetsu, which hides part of the handle. The extra blades are ondulating and semi-transparent, and similar to tentacles. When these extra blades are attached to a surface, they become invisible until they are triggered, in which case they become thin glowing lines which extend into blades.

Abilities
It is a specialized offensive Trigger that can sprout ribbons of wavy light (in addition to the main blade) and attack opponents with them. Their number changes depending on the user's Trion: Jin creates 11, Miwa around 6; someone like Chika would create about 50 or 60. The ribbons are not solid blades that can be used when swinging Fūjin but act as indicators of how many ranged slashes are left to be used. The blades transmit a slash attack that travels along the surface of objects (including walls, floors, and ceilings) and emerges to strike anywhere that the user can see. Being in an enclosed space with a Fūjin user may create hazards for the opponent, as the slashes can be transmitted to strike from odd angles in that situation. When no ribbon is left, the user has to "recharge" them before using them again, which could give opponents an opening to attack. However, when combined with Jin's ability to see the future, this weakness can be countered. Fujin's main blade can also be use to fight in close quarters combat, though its power is roughly the same as Kogetsu.

Black Trigger Capture Arc
Jin used Fujin to stop the agents sent to steal Yūma Kuga's Black Trigger. After defeating them, and in so doing increasing Fujin's perceived value even further, he gave it up in a bargain with Masamune Kido to allow Kuga to become an official Border member.

B-Rank Rank Battles Arc
According to Kodera, due to the specific nature of Fūjin's attacks, Fūjin will be stored at headquarters and used as a tactical weapon. It will be available to all of the compatible candidates for use on an as needed basis. All candidates will be trained to use Fūjin with Yūichi Jin as their instructor.

Jin uses it during Galopoula's blitz to defeat Koskero.

Users
Sōya Kazama, Jun Arashiyama and Kitora are also compatible with Fūjin, however, they all refused it.

Trivia

 * "Fūjin", when written with the kanji "風神", is the Japanese god of wind, also known as "Fūten".