|This article is about a/an condition in Mirai Sentai Timeranger.|
The Osiris Syndrome (オシリス症候群 Oshirisu Shōkōgun) is a physical malady known to the people of the 30th century that affects the heart due to the effects of space travel on some. In the original future where it is known, the disease is incurable and anyone who has it will eventually die due to overworking the heart to the point of exhaustion.
Ayase of the Timeranger possesses this disease even prior to his joining the Time Defense Bureau and kept it secret from his teammates outside telling Tatsuya Asami about it until an incident nearly weakens him to the point of near-death. He hoped to keep the disease hidden in hopes of using his final years alive to do good in the world to make up for his life prior.
Due to the manipulations associated with Captain Ryuya's ultimate plan of using the G-Zord incident and possibly the Great Annihilation to manipulate the past, he created a future where a cure for the Osiris Syndrome was finally found. Despite this, Ayase kills Ryuya in response to his defiance of preventing the team from going back to the past to help Tatsuya stop the Great Annihilation. The future created after the event and the Neo-Crisis mecha was stopped is unknown and it is unsure if the future where a cure for Osiris Syndrome still exists.