The official website for To Your Eternity Season 3 confirmed that the anime will premiere in October 2025 on the NHK General channel. Crunchyroll announced that it will stream the third season as it airs in Japan as well.

To Your Eternity Season 3 was originally announced back in March 2023, and it was confirmed to be an adaptation of the manga’s “This World” arc. Crunchyroll is currently streaming the first two seasons with English subs and English dubs.
Yoshitoki Ōima launched the manga series in November 2016 in Weekly Shōnen Magazine. The manga’s first arc ended in December 2019, and the second arc ran until October 2022. The manga’s third arc has been ongoing since January 2023.
Lastly, here’s an overview of the anime series, via Crunchyroll:
In the beginning, an “orb” is cast unto Earth. “It” can do two things: change into the form of the thing that stimulates “it”; and come back to life after death. “It” morphs from orb to rock, then to wolf, and finally to boy, but roams about like a newborn who knows nothing. As a boy, “it” becomes Fushi.
Through encounters with human kindness, Fushi not only gains survival skills, but grows as a “person”. But his journey is darkened by the inexplicable and destructive enemy Nokker, as well as cruel partings with the people he loves.