MTL - Treasure Hunt America - Chapter 4 This guy is tough enough

Roy’s life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
…
It’s really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!

I, an ordinary high school student, Kimizuka Kimihiko, who easily gets involved in things, was appointed to take care of mysterious attache cases by mysterious men in black suits. After meeting a beautiful angel-like detective girl, named Siesta in a hijacked plane, I became her assistant.

And from there–

[You deal with the beehive, and I’ll restrain the enemy.] [Don’t make plans that make me the victim.]

We had those kinds of foolish conversations, all while being completely broke every day and fought against . Even when there were hurricanes, the weather-beaten duo sleep past it. Sometimes when we saved money at a casino, we would jump around on the beds at a resort hotel, only to be broke again the next day. We would walk through deserts, traverse through jungles, conquer mountains, cross oceans– The great detective and her assistant would go through these dazzling adventures–

Until she died.

And this story starts from 1 year after that incident.

I’m the only one who’s left, but I carry on her remained wishes.

This story is far from over..

Though it felt a little awkward to be my good brother’s aunt, it was really exciting to find out how handsome and rich his uncle was.

- Description from Novelupdates