The third season of Fumetsu no Anata e. 
The story of Fushi the immortal enters the modern era.
 
Following the battles in Renril, Fushi, like a tree, spreads his roots throughout the world, fighting to eliminate the Nokkers. Hundreds of years later, having completed his mission, he awakens in the modern era. He enjoys a life of peace, free of enemy threats and surrounded by precious friends, new and old. But ominous shadows grow near yet again. Enemies that enter into the fissures of the mind. And Fushi learns of the true goals of his creator, the Beholder.
 
Faced with new trials, the time approaches for Fushi to make the ultimate decision.
 
(Source: NHK PR, edited)

To Your Eternity Season 3