Responses
@blazing... it's a room with a bed not a passage.
Ah yeah, and seeing how the assailants came from above, I'm sure Asami already knew they couldn't use that escape route. Which is why they're staying put. My concern is since the attackers didn't see them escape (or die) they may be assuming he has a panic room.. Or what if they have blueprints of his house? It really could end bad, but I hope they get out!
According to this draft of Asami's apartment, there is another passage to the panic room on the right side. I don't know where it leads though, because from the picture it's hard to say (maybe another balcony or something?).
http://www.mangago.zone/read-manga/you_re_my_loveprize_in_viewfinder/mh/v07/c046.5/27/