Responses
Maybe she was physical abusing his (actual) sibling
ohh the "elder brother" at the glitzy house? that makes sense. Maybe he was the mom's son, but with another man, based on his cautious demeanour
honestly this makes much more sense that Ameri killing bloodthirsty yakuza man so efficiently that no one suspected foul play and he just died a natural death. Esp given how Ameri's not the most efficient killer (or was nishioka (that cockroach guy) just that tough to kill?)
the question now is, why did he kill his mom whom he loved despite her negligence? was it for the negligence or could it be some other factor? is yuuma in danger (well, yeah he is rn, but i mean is he in danger of Ameri turning on him)?