Scales allows the user to form hard scales throughout their entire body, which they can either use as protective armor, or fire them off as projectiles. According to Hiryu's costume notes, growing scales requires collagen and calcium.
The generated scales resemble those of a reptile's. They are quite hard and sharp, hurting anyone who comes in contact with them. For the same reasons, the scales make for dangerous projectiles, with Hiryu being capable of launching them. The launched scales can cut through Vines and even damage solid metal structures.
Hiryu's usage for his scales can vary depending of the situation he's in.
Thanks to Scales' versatile abilities, Hiryu can battle competently at both close range and long range, switching between hand-to-hand combat and shooting when most convenient to him. If a target is not close enough for him to engage in close combat, he will start firing off scales in an attempt to hit them. Hiryu has amazing accuracy, being able to hit a small target attached to an ally without hurting the latter and from a reasonable distance. If Hiryu detects an imminent counterattack from an enemy, he can cover himself with scales in order to defend against the incoming strike.
Hiryu wears a pair of Scale Gauntlets that store the scales produced by his arms, and can fire them off in a manner similar to a gatling gun, greatly enhancing Hiryu's ranged, offensive power.