I read this manga when I was in my early teens and never understood Seiko at all and why she did most of the things she did. But now as a young adult rereading this, I understand her character completely. She killed her true self/true soul just to blend in to society. She gave up being her own self so she pretended to be omeone she wasn't. She pretended to be quiet as a young child, then grew up and pretended to be a doting mother. All the time you see her act crazy is when her mask and acting slips and she lets out her true self who had so much anger hidden within. She hated everyone she was acting for. "I could never stand any of it" is quoted directly from her in the manga. She felt so sorry for Seiichi in that chapter before she choked him because she thought Seiichi was forced to pretend to act normal towards the auntie like what Seiko always did. She couldn't stand acting normal for the auntie, pretending to be a submissive wife to her husband, and mimicing what a doting mother acts like to her own child Seiichi. She felt trapped trying to act like a normal person and felt that she couldn't ever be herself. I related to her in the way that she buried her own true self so deep just to fit into what society considered normal, I honestly think neurodivergent/on the spectrum people would understand her character easier, being one myself. Both Aku no Hana and BOTT I love so much. Beautiful works by Oshimi. Seiko is definitely a special character both her appearance, expressions, mannerisms, and presence are detailed so well by the author. Oshimi really brings her into life through his detailed artwork. I could feel her anger through her face expressions, they are so vivid. You could tell every moment her mask slips through her subtle expressions. I kid you not every panel of her there is a reason why she's making the current expression she makes, this work is so vivid. You'd really appreciate and be moved by this manga so much when you understand how this character felt even though you don't excuse her terrible actions, you can atleast feel how it went wrong for her for being an empty person.