Quoted By:
>Yajima: "The scene had her riding on the escalator for a bit, and then she ran back up and kissed him. Naturally, the escalator will take her down again, right? So while she's kissing him, she'll be pulled away. That's the scene that I wanted to make."
>Also, from the screenplay, Ash is actually dazed by Serena's kiss, rather than "he showed no reaction" as a few others may have speculated.