Yaoi is fiction. These topics have been around since forever. If you have been reading yaoi since young and have read old school stuff like Haru Wo Daiteita, Zetzuai , Junjou Romantica, Sensitive Pornograph or even Gravitation, you"ll know that in yaoi not all couples that are formed are healthy or go through healthy pathways to get to a relationship. In fact, many yaois feed off of the twisted and dark narratives to prove a point. There are tags, if you don't wish to read something because it doesn't align with your morals, don't.
Oh, I am sorry. I didn't know that. I could see though that the group translating this is a bit aggressive, but I assume they would at least tag it appropriately given the way in which they scrutinize people that "didn't read the tags" or "knowing that has rape still read it". I honestly just dropped this manga. It's not worth it, there is a lot more out there.
So this is what I think is going on. In the madarame hierarchy of people with animal spirits, merman are heavy seeds with unstable bodies. Hence a ritual was held, to contain souls inside norman's bodies and keep them enclosed and stable, like the people said "you can't even see the main soul anymore". It is possible that as part of the ritual, members of the clan are both familiar with the enclosures used and how to maintain an equilibrium. Judging by the circumstances of the uke: The seal is hereditary, you inherit those souls as a merman and a madarame, and his is particularly within his body and is very complex. One of the members of the clan's son, is actually a detonator, he has the "key to open that box" and when detonating, he revealed what other members knew all along since young: That, that father was to be "absorbed" or inside with the other merman souls, hence why "you can't even see how many are there". My argument is that the soul being maintained, is the one with the long white hair, which is the heaviest, purest and most unstable seed, that's why he said "you can see my main body right?" To understand this story better, we got foreshadowing of merman in the previous story, and saw how one guy's unstable body barely allowed him to regulate his body temperature, control his shape and he lived in an aquatic enclosed space. In the madarame, heavy seeds are to be preserved and carried on, but especially protected when they are rare and unstable, like Kunimasa's brother, how has a very hard time regulating his body temperature at times, or it was like that until he found a partner that is a heavy seed like him. So in this particular story, the Uke is being kept sealed, for the better of merman and madarame, he is to be neutral, balanced, enclosed and the same, just likes him and wants to be with him, but he happens to be a detonator.
Actually, after re reading I get it better. Haruki Madarame is inside that Thombstone that is actually a bomb. But there is something I still don't understand... why would Makio be Haruki now, what do the Madarames do to maintain their souls... I know merman are unstable, Haruki was particularly lusted over and the teacher (uke) was born with a sarcophagus very complex that they can't touch but protect so it won't detonate, apparently it has physical consequences because the school was evacuated, but Issei (some and student) is a half heavy weight and a serpent, aside from a detonator or a tomb reaper (?). There is a chance that his father, knew Haruki wasn't dead but inside, hidden in a thombstone and the uke is just a vessel. Additionally, we know that Haruki is related to Makio Madarame and that this side story takes place in the sister school of the main couples, were the child of Yonekuni and Kunimasa's mothers (Makio and Karen together) attends. We also know, based on the charts, that perhaps all attracted to Haruki because he is the heaviest seed and at the top of the madarui pyramid, a merman.











Gosh. You guys make me love mangago so much more. I am dying over here lolol