The way I see it, Yuki loves Imouto. Imouto loves onee-chan, and onee-chan loves sensei. Cool sensei also loves sensei. So it's basically a line of fuck. The line of depression.
I love Komachi. She's the kind of person who'd watch the world burn, babies and all, and find it romantic if Ako was there to hold her hand for it. Just the best.