That Time I Met A Cowboy In Outer Space
The story takes place in a modern setting where living beings have evolved to colonize Outer Space while having an Military regiment that's run by a Monarchy,
Things go south when a mysterious attack took place on the royal castle during the main character's, that is, the prince, Tommy Oldton's 10th birthday, in which, his parents died. Learning from this loss, this story takes place when Tommy is a trained martial artist with powers derived from this universe's power system, "Binding Energy", similar to Ki or Chi from Shounen manga, at age 15 and decides to dress up like a cowboy and become a hero to save anyone else who could fall victim to such attack while also uncovering the rather "Occult" mystery behind the attack in such a modern era.