You Know Perfectly Well is the first chapter of the third Durarara!! light novel.
Two years ago, Izaya Orihara visits a hospital ward where a young teenage girl lies unconscious. He approaches Masaomi Kida and provokes him as well as sternly reminding him his guilt and distress that consume him will affect his future actions and will forever be tied down by the girl, no matter how hard he tries to run away from her. When the girl wakes up two days later, the Masaomi does not visit.
In the present, Masaomi is visiting Anri Sonohara and other friends in the hospital frequently in the days following the slasher attacks. After their release, he comes to visit the girl, Saki Mikajima. She asks if he is returning to "that side," and he insists they are over and leaves. She quietly encourages him to date other girls, knowing that he will choose her over the others when the times comes.
- Izaya: "You cannot escape her anymore. Your guilt toward her will become your past, which means that, in a way, she has become your god. She is absolute. But that's not so bad, is it? After all, you love her, don't you?"
- Saki: "...You'll still come back to me, you know. And for all the mountains of love you built with other people over the years, your love for me will stand even higher, higher, higher. It will happen - it will happen without a doubt. After all, that's what Izaya said."