Whirlwind grants Inasa complete control over the air around him.
Inasa is able to manipulate gusts of wind with little to no movement from his body at all. These gusts resemble tornadoes, being powerful enough to break apart solid ice and send people flying. This allows Inasa to handle several objects at once.
As high temperatures are known to push air away, large amounts of fire may affect the flow of Inasa's wind, disrupting his control over his Quirk.
Offensively, Inasa often sends strong gusts of wind at his opponents, blowing them away. For defense, Whirlwind is effective at deflecting projectiles.
With aid from his Hero costume, Inasa can create a small tornado beneath him and fly through the air.  Inasa has great and subtle control over his Quirk. While rescuing people during the hero licensing exam, Inasa was able to delicately float people while clearing away rubble by using a countless number of different wind types to match the size and weight of everything he was carrying. 
Whirlwind in general doesn't work well with Shoto Todoroki's Half-Cold Half-Hot due to the latter's heat compromising wind flow, however, if both Inasa and Shoto are in synchrony with each other, they might be capable of creating a powerful fire spiral technique.
- ↑ My Hero Academia Manga and Anime: Chapter 109 and Episode 57.
- ↑ My Hero Academia Manga and Anime: Chapter 110 (p. 1) and Episode 57.
- Wind - Wikipedia article on the process that Inasa can manipulate with his Quirk.
- Flight - Wikipedia article on one of the abilities that Inasa can utilize with his Quirk.