Some comments on here ask why this title is josei... That's because it's for people who can really see the complexity of each character. Each had their quirks, their flaws, their reflections, their stubbornness... They were so real.
Also, lots of times, in shoujo manga the main protagonist girl isn't actually ugly or you can't understand why the male lead (Who's amazingly handsome, of course) would fall in love with her. This makes you understand. Yuri was amazing; despite her flaws, her empathy and warmth melted everyone and this was apparent to the viewer. You truly fall in love with her, all her humor and love...
Additionally, Sumire's feelings towards his dead lover are also spot-on. And yet, he is not abusive towards Yuri. Looking deeply at this manga, you can see that really, Yuri and Sumire were meant to be. And Yuri is the quintessential example of a flower. She might have seemed misshapen, but she was indeed a flower in bloom.
SPOILER:
Lastly, I cried at the end, when Yuri lost all of that weight while thinking of how much Seri would have liked to wear that and wed Sumire. The inevitability of life... Yuri had already gotten over that and have saved Sumire too, through her sincere resolve to love and remember Seri... This is really a "healing" manga, especially for adults. It soundly communicates that the value of someone lies beyond their exterior.