Panel 1: Remilia: I am not pleased with people doing what they want in my Scarlet Devil Mansion. Onomatopoeia: Kukuku (evil laughter) Remilia: It's important that I make [the perpetrator(s)] say "kyaan!" and completely change by teaching [them] who's the master [of this place].
I know the second sentence's translation is shoddy. Sorry. :/ You get the idea, though, right?
Panel 2: Sakuya: They were over there, mistress. Remilia: It's quiet or something like that. Wasn't there playing with friends?
I suppose the first sentence for Remilia might be better off as a simple "it's quiet".
Panel 3: Narration: During a midday nap Chen: Yeah, yeah, I get it... Marisa: Yuu. Remi: It's warm and feels good! Reimu: Kukaaaaa~ (Snoring?) Patchu: Mukyun
Panel 4: Sakua: Kyaaaaaaaaaaaaaaan!! Onomatopoeia: Kasha! Kasha! Kasha! (I suppose this is either flashing of the camera, or the photo taking noise) Remilia: You are going somewhere.
Yeah, I suck. I'm guessing that Remilia's point is that she's telling Sakuya to go elsewhere. The problem is that I'm not used to strange conjugations of verbs. =_=
The joke, besides the fact that Sakuya is gay for Remilia, is that Sakuya is saying the same "kyan!" that Remilia said she'd make the intruders/pretenders scream out.