Wow you have some guts I've never done that. even my own parents don't know i read this (if they found out they would kill me)
I think it was this one +couple of next pages.
http://www.mangago.zone/read-manga/hoshi_no_yakata/an/hoshi-no-yakata-chapter-25.html/4/
I told him something about Sakurai being an evil demon who is injured and that Nanasaka (I didn't actually tell him their names) was trying to exorcise him or some bullshit like that. Then I went on my way of telling him how weird manga can be... He seemed to believe me, and later forgot about it (thankfully). :D
Did anyone else read it in a public place for the first time?