I am takening an EXTREME guess based on my limited japanese (comounded by the slurring), but I think the reimu on the left is saying something along the lines of let our sister go, though if it is, it is a VERY non standard way,
いもうちょを : little sister (but note that the marisa on the right is refering to the held reimu as big sister)
はねしちぇ : let go (extreme slurred)
あげてにぇ : not sure, but the dictionary I have tells me it means something along the lines of "all" ,"whole" or "en masse" (あげて at least, I am assuming that it is just slurred) (though google says it means "to give", which means that she is saying something along the lines of "let go of my little sister and give her back", but in a very wierd way)
I think this is the same artist that did flower badge reimu, as the style is the same, (esp. the text boxes, normal yukkuri talking being a font, with shouting being drawn with a mouse), did we ever get the name of that artist?
Top right box: Fifteen minutes later Left of koreimu being held up: We'll go home, sho putch Reimyu jown!! Below that: I'm shcared of heightch! Left of koreimu: Nwo, nwo, nwo mwore, I hate heightch! Right komarisa: Don'ch bully Maricha's shischer! Koreimu below that: Fowgive her... Komarisa in the middle: Maricha will chave you! Left koreimu: Letch Reimyu's shischer go!
@alphamone: In this case, あげて means "to do the favor" so はなしてあげて means "do her the favor of letting her go", implying a (relatively) polite request. It's mostly like that when it comes after a verb.
Nwo, nwo, nwo mwore, I hate heightch! Letch Reimyu's shischer go!Don'ch bully Maricha's shischer! Fowgive her... Maricha will chave you! We'll go home, sho putch Reimyu jown!!
I'm shcared of heightch! After 15 minutes.