Kazaana

The was a curse placed on Miroku's grandfather by Naraku; it would go on to become Miroku's most famous technique. It appeared to be a black hole shaped on a person's palm. Once every year the wind tunnel grew larger and the wind became more powerful until eventually it swallowed up the unfortunate wielder. It has been shown that the wind tunnel can be damaged and expanded unnaturally.

History and Uses
Fifty years ago, Miroku's grandfather had his hand pierced by Naraku, who had disguised himself as a pretty girl. After being branded with the curse, Naraku told him it would pass throughout every male in his entire family. Soon after his son was born or in childhood, the Wind Tunnel swallowed him up. Also, when Miroku was in childhood the tunnel swallowed his father up and Miroku was stopped from coming to his aid by his father's friend Mushin, who didn't want him to suffer the same fate.

After meeting Inuyasha for the first time and battling him, Miroku showed him his Wind Tunnel and after telling him his story on how he got it, Miroku helped him and his friends by using it to suck up many demons, minus poison-bearing ones like Saimyōshō and others.

In Chapter 543 of the manga, Miroku's Wind Tunnel had reached its limit and he was forced him to use it sparingly. However, when Naraku had been reduced to a head, it started to close. After Naraku dies, the curse is finally lifted and the Wind Tunnel disappeared for good. Though in the second InuYasha movie, it is shown that Naraku can remove the curse on his own will, as well as place it back on.

Trivia

 * According to the official guide book InuYasha: Zusetsutaizan Ōgikaiden (translated as InuYasha Profiles), Miroku's Kazaana can suck up to 600–700kg massive objects. Takahashi also added that if there is no obstacle during the functioning, the Wind Tunnel would probably work more effective than usual. However, when compared with Inuyasha's Kaze no Kizu, whose maximum height of attacking enemies is up to 80 feet from the ground, the Wind Tunnel can suck up things which are 100 feet from the ground.
 * In the anime, originally, when Miroku opened the Wind Tunnel, a flash of light would illuminate, perhaps meaning the seal coming undone. During the Final Act, purple energy surrounds the Wind Tunnel's opening. Also, how the wind pulls in has changed; in the Final Act, it spirals inward, but before it did not.