@Moist_Godzilla there are 2 scrubber stacks / mufflers for exhaust gas. It seems to me that the artist took a real photo of an internal combustion engine truck and vectorized it, then drew over it, but left in the exhaust parts.
Hm..... the idea of taming a person seems really strange, and then becoming physically strong just because you tame a strong person. Seems like a really strange permutation of a typical manga slavery story, like Roxanne and Sherry, mixed together with a typical kicked out of hero party...
I don't understand. If I tell you to hand over all of your things to me if i beat you in an arm wrestling game, and if you win then you get to keep them, should you agree to the game? What could possibly make you want to agree to it if there is nothing to gain, but everything to lose?
You can read the raw LN. I read to the end. There are several more arcs. I thought there was a lot of interesting ways to expand the story, but sadly it narrowed down to a few specific ideas. And as most Japanese stories go, things get very unbelievable towards the end.