Maybe. Or it could be taken from German. 'Farben' means colors, and 'Kasten' means boxes. 'Farbkasten' means paintbox(es), and the author could've just preferred to keep the words as two separates.
+ Although Faber Castell is a German company too, I think.
Yup! Their headquarters are in Germany. Though looking at it, I seem to have made a mistake, and it's actually a coincidence for the store... Sorry!
Faber-Castell is actually someone's name. Kaspar Faber was a cabinet maker, and the business was carried on through his great-grandson Lothar, who eventually had a granddaughter that married into the Germanic "House of Castell", and adopted the name "Faber-Castell".
Admittedly, that's one hell of a coincidence for Farben Kasten to seem a lot like "Faber-Castell". Even carry similar products.
In case anyone is interested, the name of the art supply store "Farben Kasten" is most likely a parody name of "Faber Castell", a real life art supply company. They always had the best inking pens and pencil crayons. <3
Sensei must use some of their products.