Sealed Armament: Izayoi

The Sealed Weapon Izayoi (封印兵装・十六夜, Fūin Heisō - Izayoi) is the weapon of choice for Tsubaki Yayoi in BlazBlue: Continuum Shift. The Izayoi is kept under a special lock that can only be opened from the blood of a person from the Yayoi Family. Tsubaki needed the Izayoi to combat both Jin Kisaragi and Noel Vermillion, since they both posses Nox Nyctores class weapons. The Izayoi takes the shape of a short sword resembling a quill tip and a book-like shield. However, it can change its shape for some of Tsubaki's attacks.

The Izayoi has a negative side-effect: as it allows its owner to control light, it steals the light from the user's eyes. Due to this, using the weapon for an extended period of time will cause the user to go blind. The fact that it causes people to go blind during the course of Continuum Shift is told in both Story and Arcade Mode. As a matter of fact, Tsubaki is told numerous times to get rid of it. It is also revealed in Tager's "Help Me, Professor Kokonoe" that along with its wielder's light, it can steal all types of light, including a wavelength for electromagnetic equipment, or in Tager's case, his radio.

It is revealed that Hazama's primary purpose in manipulating Tsubaki to fight her comrades was to gather its power until it overwhelmed Tsubaki, bringing it under his control, and then creating a space through it that neither Takamagahara nor the Amaterasu Unit were able to observe.

In Blazblue Phase 4, it was revealed that the Izayoi was wielded by Ayame Yayoi, Tsubaki's ancestor during the Dark War.

Trivia

 * In Tsubaki's bad ending, Tsubaki dies due to the over-use of the Izayoi, as she mentioned that she already know that it will take her life. However, this is not canon. In Noel's arcade mode, when she faces Hazama, he comments on how Tsubaki's strength is "fading", implying that eventually the Izayoi may kill Tsubaki.
 * The name Izayoi means "sixteen-day-old moon" in Japanese. A sixteen-day-old moon has just passed its fullest phase, so it is at this point that its brightness begins to decline. This is another clear reference to Izayoi's blindness-inducing nature.