This is the best way I can summarize the plot and what it means

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starting off with the plot twist - it's bait and kill (uke is the willing bait, boss (not ml) is the kill). Uke is an abandoned asian kid in some western (?) village, because he stands out and is pretty, he's taken in by some men who makes him do labor and gang grape him regularly, having enough of it, he approaches the village boss who lowkey has a puritanical fetish for justice- he's all for order/morality by any means necessary. Uke tells him that he's being abused, boss rebuts that it might be him who's to blame for the moral corruption not just of the men that he accuse but of their community itself, uke answers back that he's just existing and they either hate or love him too much for no reason + he'll prove that he's truly being abused, boss can see for himself and if he decides he's the one who's corrupting them, he can kill uke himself. This is what we get at the end of the epilogue when the boss shoots the grapists.

Now fast forward to the main story, uke seems to be living with the boss, it's implied that they are "partners" coz the staffs call him brother-in-law but the boss doesn't seem to have any romantic/sexual relations with him, instead they have this odd setup where uke sleeps with other men while the boss just watches. I don't see this as him being a cuck, I think this is a continuation to their first arrangement-- that the uke is still proving the immorality of men to the boss and the boss offs them for it. The uke literally said it in his monologue- that he brings out the sinful tendencies of these men and if they succumb to it, then that just proves how sinful they truly are at their core; the boss being the moral puritan that he is, eliminates these "sinful" men who he thinks is weakness to their community/god. It's a cleanup operation specially since lust/greed are sins that can be masked by pretty appearances or words which makes it harder to judge (vs gluttony for example or wrath which are more straightforward).

Basically the plot of the main story is the ml being observed if he'll crack- and he did, even after being given a warning, he was too consumed by his sins that he was willing to give up even his freedom. In the end, he was killed by the boss (not shown but we know it's him coz it's revealed in the epilogue that it's him who does such things). Now you might be confused like me for a bit about that dude who caught ml with the uke on ch3, that ain't the boss, that's the staff who warned ml to just get through with the nightly duties and get out once he can. I assume he's loyal to the boss coz he didn't join in like those previous fucktards who kept uke + ml is excommunicated the next scene. Uke comes off as someone who believes men are scum coz of what he went through, and if someone looks at him too intensely like the ml when they first met, he raises this to the boss, but the boss can't kill him just coz the uke says it, so he pulls tactics to crack the target and prove his point. Also to add merit to the title, unlike other men who cracked because they simply lusted after uke (they even gbanged him, remember?), the ml is different coz he cracked under greed to possess uke for himself.

Those last panels are obvious symbolisms from the author for punishing literal men (tattoo) who are absolute jokes (card) for touching (hand) what they shouldn't. It's presented as a gift because it's a type of justice that the uke (who's a proxy for victims) wants himself.