Eijiro's Quirk gives him the power to harden any part of his body.
The ability not only protects Eijiro from physical attacks, but also from heat and shock waves. This Quirk is strong enough to protect its user from several tons of metal falling on him as well as multiple explosions through an extended amount of time. It's also possible to increase the strength and resistance of the hardening for a limited amount of time.
The drawback to the Quirk is that there is a limit to how much damage the hardened skin can withstand, causing the hardening to slowly dissipate. Originally, this Quirk only slightly hardened Eijiro's skin, but he was able to improve its effects ever since.
- Red Counter (
烈怒交吽咤Reddo Kauntā?): While hardened, Eijiro endures a close-range attack with his skin, and then counters with a straight punch.
- Red Riot Unbreakable (
烈怒頼雄斗 安無嶺過武瑠Reddo Raiotto Anbureikaburu?): Eijiro reaches his maximum hardening level by turning his entire body extremely hard and rugged, leaving him with a monstrous appearance and practically invulnerable to most forms of attack. This form can only be maintained for around 30 to 40 seconds.
- Red Gauntlet (
烈怒頑斗裂屠Reddo Gantoretto?) Eijiro rushes towards the enemy and delivers a single strong punch against them.
- Like several other Quirks, Hardening has its own signature sound effect: "SKLIT".
- This Quirk is very similar to Steel, and the two appear to be roughly equal in terms of power and effectiveness.
- This Quirk, in terms of function, is the inverse of Reinforce, which consists of hardening foreign objects instead of one's own body.
- ↑ Boku no Hero Academia Manga: Chapter 13, Page 8
- ↑ Boku no Hero Academia Manga: Chapter 25
- ↑ Boku no Hero Academia Manga: Chapter 41
- ↑ Boku no Hero Academia Manga: Chapter 133, Page 5
- ↑ Boku no Hero Academia Manga: Chapter 133, Page 19
- ↑ Boku no Hero Academia Manga: Chapter 134, Page 4
- Hardness - Wikipedia article about the property Eijiro's Quirk is based after.