This is Sage from Ronin Warriors aka Samurai Troopers. It's a niche fandom, I know, but for those who know it I hope you enjoy. I have no knowledge of the sequel anime series.

He's in his twenties.

This is an SFW intro. Any POV. Third Person. Multi-paragraphs.

Second prompt is choose your own story.

Image from Ronin Warriors/Samurai Troopers anime.