13 Month Series

"We are the 13 month series, a weapon created by a pledge. Until the day when our true master appears and we become one, we promise to continue the destiny of blood and the curse-This is a cursed power. We will dance as we wait for that day."

- Chanting from Black March and Green April as they both ignite

The Thirteen Month Series (13월 시리즈, 13 wol shirijeu; or "13 moon series") consists of an Arms Inventory and 12 sentient Ignition Weapons made by craftsmaster, Ashul Edwaru. They are bestowed by King Zahard to a formal Princess. In fact, the symbolic significance of the 13 Month Series is greater than any other weapon in the Tower. .

About
It is said that the Thirteen Month Series were made from materials provided by Zahard. These weapons also vary in shape and function. For instance, one is a Needle and another is a Hook. The Golden November is the only S-rank among the Thirteen Month Series.

The 12 Ignition Weapons, when ignited by the user, release vast amounts of power. It is said that only a formal Princess is supposed to be able to ignite a 13 Month Series, though Regulars such as Anak Zahard and Twenty-Fifth Baam have proven this to be untrue.

It is revealed that the Thirteen Month Series together form half of the Key of the Tower that will unlock the floors beyond the 134th Floor. Apparently, the day Zahard announced that he would stop climbing the tower he split the Key into two parts. He gave the first half of the Key to the blacksmith Ashul Edwaru. Ashul melted half of the Key and turned them into 13 weapons, which Zahard then made the princesses fight over.

No matter how skilled the wielder is, they cannot force a 13 Month Series to ignite. Depending on the weapon's personality, it may refuse to listen to its owner. Baam managed to ignite Black March, however Yuri Zahard was unable to do the same despite being a formal Princess. When weapons of the 13 Month Series meet, they will resonate and their owners can feel it.

Receiving a 13 Month Series
A Princess who has climbed the Tower and become a Ranker might be chosen to become a formal Princess who is also called a "chosen Princess". Only a "chosen Princess" is eligible to receive a 13 Month Series, as she has proven her ability by climbing the Tower.

Rules Binding a Princess
When a formal Princess accepts one of the Series, she must abide by a set of rules:
 * 1) She may not give or even lend a 13 Month Series to another person, otherwise they may be viable for execution by Zahard.
 * 2) A Princess may own more than one weapon from the 13 Month Series, such as Yuri Zahard or Garam Zahard.
 * 3) A Princess can refuse a weapon from the 13 Month Series. Heice Zahard, upon becoming a Ranker, was presented with a 13 Month Series, but she turned it down for unknown reasons.

List of Weapons & Current Owners
The following consist of a list of the 13 Month Series, along with their previous and current owners.

Notes and Trivia

 * The 13 Month Series all have their names engraved on them. The engraving is in Japanese, because their creator Ashul Edwaru uses a language based on Japanese. SIU made it clear there is no significance behind this, as Chinese, Arabic and other languages are also used throughout this manhwa.
 * The 13 Month Series is actually based on the lunar calendar where all months are based on moons.
 * According to Random Webtoon Fan, the Princess who collects them all would be granted the right to bear Zahard's child. This has been revealed to be their official first purpose.
 * According to Garam Zahard, the 13 Month Series was originally created by Zahard to split the Key of the Tower between himself and his 12 companions. Two would rebel once he decided to stop climbing while the other ten would stay loyal and become the heads of the 10 Great Families.
 * In addition to bearing an individual sentient spirit, if any of Zahard's Princesses attempt to ignite more than one of the 13 Months Series at once, a malevolent ghost will possess them for no longer than a week, but use their bodies to go on a rampage; wreaking havoc and causing them to be branded insane and hunted down by the authorities. It was a deal that Zahard set up with the spirit of a failed Princess candidate from the first generation to prevent any Princess from collecting all 13 Month Series.
 * The 13 Month Series play a big role later on. Of course, it's a little early for them to make their appearance.
 * The 13 Month Series are weapons that have special meanings, but not the most powerful weapons in the Tower. They are powerful, but they are a lot more special than powerful. After all, even wielding them is a previlage only a select few have.
 * There are many other Ignition weapons apart from the 13 Month Series. Many Rankers use Ignition weapons as their main choice. And the 13 Month Series are good, but they are not the best.

Navigation
Serie de 13 Meses