(warning for discussions of incest, social oppression, and canon-typical violence/sex. also, spoilers. read with caution!!)
There is something to be said about the ways in which MADK manages to layer its coding of the various supernatural and demonic elements of its story into something extremely human and true to life, both on an individual level and a broader social one.
The more obvious way that I think a lot of people pick up on this being expressed is through the ways in which violence and sexuality are so deeply entwined. From the start, Makoto's sexual deviancy can be interpreted both as his more violent/sadistic tendencies and as his queerness, to the point where it is unclear at the start of volume two if Makoto's father is more disgusted by the fact that his son had been participating in an occult ritual or engaging in sex with another man. This is key to the early features of his relationship with J, the thing that caught both of their attention being the way in which J recognizes Makoto's suffering through how he is isolated and alienated and shunned from society for his sexual attraction.
This theme extends further when we look at the cycle of abuse that sits at the center of the narrative. In particular, I think it's important to note the way in which incest, and especially father/son relationships, sits at the core of this cycle as the ultimate incarnation of this confluence of violence and love, the ultimate form of abuse and sex combined. Speaking again about that scene with Makoto's father, it is notable to me that the only way in which his dad is able to come to terms with his grief is through the symbolic killing of his son, by driving the (phallic) dagger into Makoto's body, thereby granting him almost immediate satisfaction while breaking him to pieces. Any love or grief he may have ever had for his son is thus expressed through the ultimate act of violence and his rage, directly killing the thing he had loathed for so many years.
Yet, from a slightly different angle, this act is also one of the first ways in which we begin to see Makoto try and get closer to J, through replication of the same abuses and (sexual) violence that J faced or, seemingly, desired. As is made clear later on, the ultimate Thing hanging over Jonathan's head for the vast majority of the story is his unrequited sexual and romantic love for W, a person who explicitly refers to himself as Jonathan's father when he first takes him in. The fact that J is never quite able to act on this love and touch W becomes especially notable when J eventually takes on W's position as Top Demon, from that point forward repeatedly engaging with Makoto sexually while also never quite allowing him the satisfaction or satiation of his hunger that he truly wants, both indulging in the very thing he had wanted so badly (albeit, from the opposite position) while also inflicting the same harms onto Makoto that he himself had once faced. In turn, Makoto also must repeatedly experience sexual violence in order to gain power over others and drag his way to the top to get closer to J. Later, he even makes the decision to have sex with Kieran after hearing him say that he had been J's first, recreating not only his own first sexual encounter with J in reverse with the throat-fucking thing, but also the incestuous relationship between Kieran and Jonathan, as another way of trying to understand who J really is and his past.
This leads into my second point, which is about the role in which racial coding plays in this kind of violent sexuality as well. In volume one in particular, it really stands out to me just how heavily it is emphasized that Makoto is this little Japanese kid, a literal Asian pet to J-- something White, European, and English, powerful to the point of being practically untouchable, sitting perfectly at ease in his Western castle like an angelic monster out of a foreign fairy tale. The moment he is killed and brought down to Hell, Makoto is dominated and oppressed by the eternally unfazed white power of J, and in the face of that he comes to desire two key things: to overcome that power and surpass it (as he initially believes, his primary motivation across the entire story), and to be seen and respected by it (as he later comes to understand nearer to J's death).
The big thing that stands out to me about this is the way in which Makoto, and later M, defines and understands his own sense of self in contrast with the overwhelming white western-ity of Jonathan the English Demon. Early on, J makes it very clear that his intention is to turn Makoto into something like himself, and in many ways this is a desire that comes true-- M is, after all, essentially his successor, the one who successfully takes over and surpasses him, is able to call him by his name, and lets him be freed of the "curse" W put on him by taking his place through sheer love and obsession alone. Despite this, Makoto still regularly pushes back on the idea that he will become exactly what J wants, and it is this desire that allows him to succeed and flourish where people like Datenshou fail, to truly overpower J.
Symbolically, I think this idea can be seen as being represented through the way in which Makoto's head never seems to fully mesh with the rest of his body, with the stitches on his neck never fully disappearing even after J's death. While M's body is something given to him in the early days of his demonhood by J, something that fits J's ideal aesthetics and allows him to fit in better with the rest of the world, his head continues to stand as the only thing he really takes with him from the human world. This is part of why I believe Makoto is able to get Kieran's wings, but is never able to get the horns he requests from J early on-- for Kieran's wings can attach to his body, something natively Hellish and given to him by his white benefactor, but his head cannot be significantly fucked with or changed, outside the swap to black eyes or his hair growing.
In general, heads seem to hold a lot of power and are often the thing that distinguishes demons as something monstrous even as their bodies often stray more human. In the case of M in particular, his head is the source of his tears and voice, the expression of his emotions and his ability to dominate and impress fear in all of those around him. At the same time, his body is necessary as the thing that he can use to fuck/be fucked with, being the primary location where he is able to engage with his sexuality, and therefore another way that he can take power over others.
edit: ADDITIONALLY, we get a slightly different take on this with the first scene with Fjord and the idea that, in order to get rid of the last remaining traces of Makoto's humanity, he has to lose his virginity, or more specifically, get fucked by a demon, since I guess fucking J's guts doesn't count... (Domination vs. being dominated, maybe?) Honestly, there's probably more to be said about the ways in which humanity is coded but those thoughts are still percolating tbh, so. Later maybe.
Again, if we're to understand violence and sexuality as inherently parallel with one another in this universe, as the way to gain power and social standing, then we can understand sexuality as the key to social oppression. In order for Makoto to truly rise to the top he must not only engage with people socially through conversation and intimidation and speaking-based psychological warfare-- rather, he must also Love his people, and in the process oppress them through violence. If we're to understand J as standing as the ultimate symbol of power throughout most of the story, the primary source of white imperial oppression and domination, then M's attempts to beat and surpass him require him to carry out the same kind of love/pain. The only way he can win is by taking everybody's attention, to oppress and overpower quite literally every other being around in his ascent to his Love, the one who violated him first, who got under his skin and seeded his obsession the deepest.
In my reading, basically everything in MADK comes down to this, to Makoto attempting to understand not only how to speak, but how to use his words and other peoples' love to get power over them. In the early chapters, this presents more in terms of him falling to the thrall of J while also verbally speaking out and pushing back on him, slowly but surely learning how to listen to the hidden words snuck between and around sentences. Later, during the initial three-year time skip, this shifts to Makoto working at the brothel and learning how to use his sexuality alongside his words to take on clients, initially using J's status to raise his own and drag himself up from the lowest ranks. After this, we see his schemes slowly and slowly get more sophisticated as Makoto learns how to play people better and find their weaknesses, first using the allure of his sex as a way of getting into the slums, and then later finding an even greater weakness in Kieran by seeing his love and twisting it and using it against him. In this end, this is what allows him to figure out the best way to take down J also-- not just by turning himself into an object of love for Jonathan, but by using J's own memories and anxieties and past loves against him.
Of course, none of this actually seems to make M all that happy. Becoming the ultimate oppressive power in Hell doesn't allow him to ever be at equal standings with J-- it only lets him overpower him, to dominate him in the way he was once dominated. M is unable to ever truly extricate his idea of love and sex from that of oppression and violence, and thus his only option moving forward is to repeat the exact same cycle, trapped in the exact same contradiction. Tragic.
