The successful film Demon Slayer – Mugen Train ( Kimetsu no Yaiba ) will receive a 7-episode , serving as a complement to its 2nd season, which arrives on December 5th.
The adapted episodes of the film premiere tomorrow in Japan, October 10th . According to reports, the first episode shows Rengoku as he embarks on his journey to reach the train. The remaining episodes will add around 70 new animation cuts and new background music.
The 7 episodes will be available from October 10th on Funimation and Crunchyroll .

Therefore, Funimation will broadcast the new anime season as soon as it premieres this year. Official Website .
Synopsis:
Since ancient times, rumors of man-eating demons lurking in the forest have abounded. Because of this, locals never venture outside at night. Legend has it that a demon slayer also roams the night, hunting these bloodthirsty demons. For young Tanjirou, these rumors will soon become his harsh reality... Since his father's death, Tanjirou has taken on the responsibility of providing for his family. Although their lives may be hardened by tragedy, they have found happiness. But this ephemeral warmth is destroyed one day when Tanjirou finds his family slaughtered and the only survivor, his sister Nezuko, has turned into a demon. To her surprise, however, Nezuko still shows signs of human emotion and thought... Thus begins Tanjirou's quest to fight the demons and turn his sister human again.”
Finally, the first season of Kimetsu no Yaiba premiered in April 2019 .