This might contain SPOILERS.
Poor Sougetsu? Really!? It seems we read a completely different manga.
Even if Shirou wasn't a saint, of course not he kept saying and everybody kept saying he was a demon, I would never think of Sougetsu as a "poor, poor guy".
Didn't you see he was a merciless boss of bandits? Does it sound to you: rape, murder, robbery, kidnapping, pederasty? Well, it does for me.
Although I don't agree with your opinion, I also can say I enjoyed the story.
I don't know why, but it was refreshing to watch these awful psychopaths who were shameless.
Yeah, there was tragedy, but somehow it was a bittersweet ending for those two.
About Chihiro, well yes, that love was as ephemeral as a sigh, but it teached Chihiro his "sins" could be forgiven and that he deserved to love and be loved in return thanks to Shirou :3 (oh! He's not such a bad guy). So, it's also a bittersweet ending for him...
And finally, why the psychos didn't have a happy ending? Hmm, they were psychos... and shameless... Sougetsu found out he loved Shirou, made love to him and promised to pursue him till he becomes his. Yay! Again bittersweet, but... it looks like it's common in this manga. And Shirou decided to live thanks to Sougetsu's healing (words and luv ;P ). Double yay! But then... run away from Sougetsu: bittersweet. Haha.
Omy....shirou is such a playboy xD poor chihiro -3- he was too cute for words....and poor sougetsu....keeps running after shirou but shirou just keeps having affairs....I can almost imagine him getting everywhere xD while sougetsu runs after him xD I bet if the story continues it would be like that xD oh well....I enjoyed the story....twas a fun read (≧∀≦)