The protagonist is hotblooded.

For those uninitiated, a hotblooded character feels extremely passionate about justice/love/protecting his friends (there are also other types, like hot blooded artists, but these are usually played for laughs) to such a degree that he WILL overcome challenges that aren't humanly possible.
Hotblooded characters regularly keep fighting after all others would've died, overcome mind control, poison, disease, gravity, radiation and fate itself by sheer guts and passion.

Prominent examples include Domon Kasshu (G-Gundam), Magami Yuuji(Only You), Kamina and Simon (TTGL) and Himehagi Aisuka (Trample on Schatten!!).