Miyatsu

was the paternal grandfather of Miroku, who was the first in Miroku's family line to be cursed by Naraku to bear the Wind Tunnel (Kazaana), which was eventually passed down the generations to Miroku's father and Miroku.

History
Miyatsu had been fighting against the hanyō Naraku for years. Each time they fought, Naraku took on the form of a different person. Naraku (At that time disguised as a woman) cursed Miyatsu with the Kazaana 50 years before Inuyasha's reawakening. In InuYasha the Movie: The Castle Beyond the Looking Glass, it was revealed that it was he who sealed Kaguya within her own mirror.

Personality
According to Miroku, Miyatsu was, like his son and grandson, quite the ladies' man (a lecher).

Powers & Abilities
Though not often mentioned throughout the series, Miyatsu was depicted as having immense skill as a holy-man and powerful spiritual abilities. Naraku evidently feared his Spiritual Powers to such a point that he cursed him with the Kazaana.

Weapons

 * Kazaana: The Kazaana, or Wind Tunnel, was a curse placed upon Miyatsu by Naraku that was be passed down through the male line in his family. The curse pierced the palm of the monk, and resulted in a black hole or void which sucked everything in range into it, creating a terrible sucking wind in the process. The Kazaana eventually grew to such a size that it sucked in its host, which doomed Miyatsu and Miroku's father. The Kazaana also suppressed some of its host's spiritual powers.
 * Sacred Sutras: These "Jufu Talismans" were strips of paper upon which special prayers have been written and prayed over, imbuing them with spiritual power and energy against specific evil. Each sutra had a special prayer, and thus was tailored for a specific purpose such as general protection, good luck, safe travel, removing a ghost or spirit, or sealing off a demon or spirit. Miyatsu's family (and many other monks) used them in their work to "exorcise" ghosts and demons from locations and people alike.

Reference
Miyatsu Miyatsu 弥萢