Kingyo no Shigai wa Numa no Soko

I have a younger twin brother. His name is Sumiyuki.
He's so stylish, and kind, and cool, and can do whatever he puts his mind to. He's perfect.
I, on the other hand... have frail body... am clumsy... and can hardly even move.
My entire life I have depended on my brother for almost everything.

And... it fills me with guilt. That I am essentially robbing him of his precious time on this earth.
Ever since we were small, he has always done so much for me. Even now... he still does.

So, I thought that I should become independent.
To release my brother from his burden and let him live his life, but...

"Why... are you not depending on me?"

It would seem that my younger brother did not love me as his "older sister," and rather as a "woman."
A woman he has willfully and deliberately guided to become totally and utterly reliant upon him.

His perverse love drowns me... dragging me down into the deep dark swampy depths----

A manga version of the audio work of the same name.

(Source: BLIC-TL, translated)