Indeed. The reason I brought up Die Hard is because Triage X reminded me so much of all the 80s and 90s action movies I used to watch as a kid in terms of action and fun. I agree with you when it comes to Arashi given how much Satou could have fucked up by turning him into a self-insert. Arashi's Highschool of the Dead counterpart Takashi is pretty bro-tier as well.
Also, Sayo is best girl.
The author of Triage X was just the artist of Highschool of The Dead.He's still alive and well and working on the manga on a regular schedule...the total opposite of Highschool of The Dead's situation...