Eren Yeager

Eren is a character from the anime and manga series Attack on Titan by Hajime Isayama..

Titan shifting
When injured, Eren has the ability to conjure the body of a titan and control it from the inside of the titan's nape. His titan is 17 meters tall and above average in strength, but cannot speak coherently. In the past he has had difficulty transforming due to doubts about what he was doing, and having a purpose to transform is a requirement, but this rarely affects his transformations.

Regeneration: Eren can regenerate parts of his titan (as well as his real body). Another titan shifter was shown to be able to regenerate one of her titan's eyes in around 30 seconds, focusing her regeneration on just the one eye so that it would be faster. It hasn't been shown how well Eren can regenerate or if it's affected in any way by training, however it has been shown to take a lot of stamina. When regenerating, the wound releases steam, making it visible to others. While Eren can regenerate without a conscious decision to, he can also prevent himself from regenerating.

Hardening: I don't really know how this works sorry

3D mobility gear
The 3D mobility gear allows soldiers to fight on equal footing with titans, both allowing them to reach the titan's weak point and providing a weapon that can pierce the titans' skin. Bound together by the harness are gas cylinders that are worn at the hips, a mechanism for holding and releasing cables with hooks on the ends (as well as holding the cable), and two hand grips. The hand grips have two triggers each, for firing their respective cables and activating the gas. They also have a hand guard which when pulled, reels in the cables. While it isn't part of the mobility gear, soldiers usually fight with a box of ultrahard steel blades attached to their gas cylinders. These can be easily inserted into or removed from the hand grips if a soldier needs to replace their blade. Both the hooks on the cables and the blades are made out of ultrahard steel (the only known metal to be able to pierce a titan's skin), the blades can easily dull within just one mission.