Dark Red-Purple Spell Book Pair (ja. 濃赤紫本組, also known as Magenta Spell Book Pair) is the pair of mamodo Zofis and his human partner Koko.
For the pairing see ZofiKoko.
Interesting facts
In official English translation Zofis' spell book color was translated as magenta. Based on this, Zofis and Koko pair will be called Magenta Spell Book Pair. In Japan the name Magenta Spell Book Pair is used for Arth and Ellie.