Follow up to my doll analysis but focusing on Kaoru now and especially the op:
I think that it's not a coincidence that Kaoru and the girl in the opening literally share the same exact color palette. Morever, her lover shares Henmi's hair color too. It isn't far fetched to believe them to be linked if not for the girl to be a direct reference to Kaoru's future fate.
The girl is clearly leaving home. Even though the focus is put on the doll, along with it we see a jewelry box, a lamp, necklaces and other knicknacks, common objects in a girl's room that are simply left behind after her departure. Of course going towards her lover means leaving behind innocence, your past, your childhood and childhood home. Hence: leaving behind the doll.
Kaoru, amongst the rest of the girls, is the one further away from the overall symbol of the doll. She is a dynamic character, always chasing change and growing. She cannot allow herself to step back or being chained to the past, because doing so would put her at a stalemate. She can either be chained by the fear of dying anyday for the next five years, or push through and move on, living as much as she can in the meantime.
She also has the most distinctive style of them all, the more tomboyish and frilly-less of the entire cast. The most further away from said doll. We can Argue that Especially Rei but Fukiko too, don't really wear dresses akin to the ones of dolls, but I do think that it is relevant that Kaoru stands out as the odd one out, and that even Rei, in her ONE fit that the anime so graciously provides us with, (in the manga she has so much more, she is a fashion icon) despite being androgynous and all, still has some frills, something that distinguishes her from Kaoru.
Her interactions with Nanako, aka our doll, are also different compared to the other characters. Her attitude is the one of a person recognising her innocence, and consequentially helping her grow. She doesn't dream of what she has, she doesn't wish to use it to try and manipulate. She recognises that it's something Nanako will outgrow, and she helps her through it.
Let's move onto the lyrics: I preface by saying that I immediatly have to scratch the idea of it referring to the Fukiko/Henmi, Rei/Fukiko or Nanako/Rei situation because the line: "the overflowing love I felt since I met you" is immediatly followed by "couldn't be possibly be held in a golden bowl" which is implied to be the bowl of happiness. In the first case Fukiko has no real feeling of happiness related to Henmi, all that she feel is mournful regret towards that summer week, and the hostility that came from Henmi non coming to her birthday party. Rei shares a vaguely similar feeling towards Fukiko, and her sentiments in anyway don't carry anything positive and are more of a curse. Lastly Nanako doesn't immediatly fall in love with Saint. Juste, it's something that takes her time to process, and even then she literally bursts into tears whrn she finally confesses. Whilst Kaoru's feelings are still infused with longing of what could've been, we are seen her remember her time with Henmi in a positive light something that had to be cut short, but could've gone on in a different settings because it was something positive that brought her happiness. (trust me it hurts to talk about the Henmi/Kaoru relationship in any kind of positive light). The lyrics "For your sake, For the sake of love, I would empty the bowls of my past" remind me of the words Kaoru repeats herself about Henmi and having to forget him "because I love you I must leave you, because I love you I must forget you..." Even the repetitive musicality of it.
Lastly I ould like to speak about the Manga ending. Being chained to the past in Oniisama e is the ultimate recipe for disaster, whilst everyone fighting change is rewarded in some kind (despite the more general sufferances that everyone in tjis franchise has to endure). Rei begins to move on, she gets better, she convinces herself that if Fukiko even loved her for a few moments she will be content with it. It's a moment of development, sure, but that is still heavily chained to something attached to their past and when Fukiko tells her that, no, she never even cared about her, Rei realizes the weight of her chains, realizes that she doesn't have the strength to move on yet, and ends up overdosing. Fukiko, stays chained to her "feelings" for Henmi and to the fact that Rei will always be a possession of hers, ready at her side. She loses both of them. I interpreted Kaoru's death as something equal to those situations. It's interesting to note that, epecially in the manga, it's usually Rei that promps her to remember Henmi exists, whilst Kaoru and her "must go forward" mentality allows her to keep him, momentarily in the toybox of her past. She has Rei, someone that is currently walking beside her in the present, despite all her difficulties. She only says to be alone when Rei dies, she never feels alone before that occurrence even without Henmi, because Rei is there, presently. The one moment Kaoru falters it's this. When she feels alone and scared, when she cannot figure which way to go. That is when she takes a step back, when out of the loneliness of her heart she goes back to Henmi and the comfort he provided her with. Especially in the manga, he almost feels like a replacement, a step-in once Rei cannot be there anymore. And I truly believe that had Rei survived Kaoru wouldn't have looked back at Henmi. But she did. And despite her using something from her past as a leverage to move forward, it dooms her and she dies too.
