The MC having a complicated childhood has been alluded to continually throughout the story, from the very beginning. His mom isn't some fake contrived plot device or some over-the-top villain. She's a hardcore narcissist, plain and simple. Shiki is not your typical indecisive simp (god I hate that term) typical harem MC and has way more depth than they do. Shiki having to deal with being manipulated, controlled and beat down by his narcissistic mother is the real core of the story, carefully hidden under a sweet layer tropey big titty harem wish fulfillment. This manga deserves the drama tag just as much as it does romance and comedy.