Chapter 20 is from volume 5 or 6? I don't know, so I'm kinda afraid to tell spoiler here. Anyway, I think you're talking about vol. 5 (with that photographer and stuff)! Well, it's fun to see Tonomine and Asuka together, but I really didn't liked that they are working secretely (I mean, he could at least tell to Ryo or Juta). The photographer appears on the next volume, to explain why he knows Asuka, of course! Dad finally shows up??? READ THE NEXT ONE! haha Man, I really wanna read volume 7! (Well, that's it, sorry if I told some spoiler, it was not my intention!).