According to Dave Meltzer of Wrestling Observer, Haybusa’s body was found in his home by the owner of a nearby tavern and his death was said to be in line with subarachnoid hemorrhage, or “bleeding of the brain”. Hayabusa died at the age of 47. He was supposed to be at a mini concert that very day. He was not just a legend but a mentor to quite a number of wrestlers including former WWE World Heavyweight Champion Seth Rollins, Finn Bálor, Samoa Joe and a host of others.
WWE.com also posted the following about the death of Hayabusa:
“An innovative high-flyer who helped inspire a generation of Superstars, the mysterious, masked Hayabusa was known for throwing caution to the wind. Ezaki created daring moves like the Phoenix Splash, which to this day can be seen in the repertoire of daredevil competitors, including former WWE World Heavyweight Champion Seth Rollins. A major star in Japan in the mid to late ’90s, Hayabusa competed in one major American match, teaming with Jinsei Shinzaki (known as Hakushi in WWE) in a losing effort against Sabu & Rob Van Dam at ECW’s Heat Wave 1998 event. Although his career was cut short by injury in 2001, Ezaki never strayed far from the industry, where he continued to impart his knowledge.”
Thanks to wrestlingnewsplus for all this info.