Null Void

The Null Void is an area that is not explored but is most commonly mentioned through different characters in the Sazeku-Ba! series. This is where people are banished for all eternity

Whereabouts
It is not exactly specified where the Null Void is. It is implied that it is several miles beneath Hell (500,000,000,000,000,000,000 beneath the surface of the earth). What is known is that all Yakians has access to opening and closing the Null Void. This is evident as Basil Jr., used this as a way of trapping both Tadashi Sakura and Riku Hiroki in there for the rest of their lives.

Significance
This area is not usually mentioned throughout the series but is more common in the films. Its first notification was in the first move, Sazeku-Ba!: Null Void, where Basil Jr. talked about how his father, Basil was imprisoned within the Null Void because of King Neptune's father, Uranus trapping him in there. Anybody who enters the Null Void is unable to escape.

Sazeku-Ba!: Null Void
Basil Jr. explained to the heroes about how King Neptune's father banished his father within the Null Void for all eternity. Wanting revenge, Basil Jr. planned on doing the same thing. He opened the Null Void and it was sucking everyone and everything with it. However, Sayuri Wanatabe manages to stop him and sends him straight into his own attack.