From author:

「ち、違うのっ！　　えぇっと・・・これはね？　桐乃・・・・お、お兄さんが、　無理矢理・・・そうっ！　無理矢理なのっ！」　「じゃぁなんでコイツ手錠なんかしてんの？」　「そっ、それは・・・・・」　「・・・・・・（死亡）」

Being Kyousuke is suffering.

"No, you're wrong! Ah... this? Kirino, your... o-older brother, he... forced me... Yeah! Forced me!"
"Alright, then why is he in handcuffs?"
"Th-that..."
".... (death)"

It just keeps getting better and better for Kyousuke.

There are a few reasons he could have turned blue...all of them are easily possible.

"ruined for marriage" tag? isn't it a bit late for that?

With this tug-of-war and escalating behavior I'm betting Kyousuke will be dead in a few more panels.

Also, wrist bruises.

Kyosuke... I pray for your body and soul as you are being used as a studhorse....

I always did like Ayase...

And Kirino and Ruri for that matter. Kyousuke should be having the time of his life, being, presumably, a hormonal teenage boy.

Except with Kirino, but that's not really the point. The only problem is the three of them knowing that the other two girls have had their fun. Girls don't really like sharing, in my experience.

OOZ662 said:
There are a few reasons he could have turned blue...all of them are easily possible.

Manhattan Project ?

TFTD said:
Girls don't really like sharing, in my experience.

More like a competition.

" The embarrassing Morning after it... ... "