[Aiko notices the person following them well before Ishimaru does; he's trained her into doing things like that, into keeping an eye on their surroundings even when he can't or isn't inclined to for whatever reason, and he can feel her tensing up nearby.
He glances in her direction briefly, even though he can't see her; just...keep quiet for now. There's no sense in getting worked up over random passersby, even if it is late...]
[action]
He glances in her direction briefly, even though he can't see her; just...keep quiet for now. There's no sense in getting worked up over random passersby, even if it is late...]