The Green April (초록 사월, Chorok Sawol; "Green Fourth Moon") is a weapon of the 13 Month Series. It was first owned by Anak Zahard who was a Princess, then Anak Zahard Jr. (Anak's daughter) and then, Yuri Zahard.

It is a Hook capable of elongating and as it's also a Compression Weapon, Ignition will decompress part or all of it. When Ignited, the Green April could turn a place into "a massive forest".

Its original form has only been glimpsed, it has sharp teeth and short, wavy hair. It might be human, non-human or even demonic. The weapon's personality is not known, as its form has been seen so little. It seems quite sadistic, and enjoys being used in combat.

The Green April is a 7B-Rank Hook, which most likely becomes A-Rank when Ignited.