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The Rainbow Undecimber (무지개빛 십삼월, Mujigaebit Shipsamwol; "Rainbow-Colored Thirteenth Moon") is one of the 13 Month Series created by legendary craftsmaster Ashul Edwaru for the Princesses. It has never been granted to a princess. Instead of a needle or a hook, the Rainbow Undecimber is an arms inventory.

Notes and TriviaEdit

• Contrary to what some may say, the word "Undecimber" is correctly spelled with an "i", not an "e". This because it doesn't entirely reference December. In calendar sytems that have twelve months, a thirteenth month, were it to exist, would be called "Undecimber".
• It is the only 13 Month Series not awarded to a Princess yet. It still lies in the possesion of the higher ups.