Incest [silent] Incest - my dad is next to me...

I've been married for five years and am a kind husband who always cared about me. I'm so glad I met this person. But I have a secret that I can never tell my husband. That's what I fell in love with my husband's stepchild, Ryo. And I even crossed a line that should not be crossed. Recently, I've been excited to have had some lewd acts with Ryo so that she wouldn't be found out by her husband. The tension that is just before I know it or not makes me even more lewd.