In this comic, Reisen and Tewi are speaking in a Tsugaru dialect so heavy as to be difficult for even a native (standard) Japanese speaker to decipher. The author posted a 'translation' of this comic into standard Japanese which is now on Danbooru as post #1045249.

Holy Christ! That's not a dialect, that's a whole other fucking language!

Tetrominon said:
Holy Christ! That's not a dialect, that's a whole other fucking language!

No wonder I couldn't "read" the comic lol.