Fierce Wings is a Mutant-type Quirk that grants Keigo two large, red wings made up of dozens of feathers. Keigo can freely manipulate each individual feather using his mind.
The fully-feathered pair of wings give Keigo the ability to fly at incredible speeds. Feathers can be detached to perform individual tasks and the user shares a telepathic connection with their feathers.
The feathers are both stiff and flexible, as a single feather is strong enough to easily move a person around. They also vary in size, strength, and even cutting ability. Each individual feather act as sensors that can feel people and objects around them by feeling the vibrations they produce. This widens the range of the user's senses, allowing them to utilize their feathers at a great range.
If too many feathers are detached, Keigo's flying capabilities will worsen and limit their mobility.
As long as the feathers remain intact, they can be reattached to the user's wings. If feathers are destroyed in some way, the main wings will regrow them within two days.
Keigo also mentions that fire is his biggest weakness as they can burn his feathers, severely worsening his mobility.
Keigo mainly uses his Quirk to fly and fight at great speed. Keigo's Quirk has made him the No. 2 Pro Hero and one of the fastest fighters in the world. In fact, Keigo subdues common criminals so quickly his subordinates only serve to mop up while Keigo moves on to his next target. His speed even rivaled that of High-End, who possesses multiple enhancement-type Quirks.
Keigo also makes great use of his feathers to save people from disaster. He can manipulate each feather and dedicate it to saving one person, using it to float them away from danger. By spreading his feathers out throughout a large area, Keigo can expand the reach of his senses to detect every vibration someone makes. He possesses great finesse and skill when using his feathers.
Despite being the current No. 2 Hero, Keigo is aware of his Quirk’s weakness and will not exhaust his feathers unless absolutely necessary. He also recognizes that his Quirk does not boost his overall brute strength very much. To compensate, Keigo can use his feathers as bladed weapons. Combined with his speed, Keigo can swiftly slice through enemies  or fire off smaller feathers from his wings like daggers.
When paired with a power-type like Endeavor, Keigo can thrive in a supporting role when facing a top-level villain like High-End. By attaching his own wings to Endeavor's back, Keigo could help Endeavor fly and granted him enough speed to compete with the aforementioned Super Nomu.
- ↑ 1.0 1.1 My Hero Academia Manga: Chapter 187 (p. 15).
- ↑ My Hero Academia Manga: Chapter 191.
- ↑ My Hero Academia Manga: Chapter 199.
- ↑ 4.0 4.1 My Hero Academia Manga: Chapter 189.
- ↑ My Hero Academia Manga: Chapter 188.
- ↑ My Hero Academia Manga: Chapter 186.