Is the adaptation of the Kimetsu no Yaiba movie Mugen Ressha-hen, the second season of the anime, or is it a mini series apart?

Question

I've seen that the Kimetsu no Yaiba movie Mugen Ressha-hen is being adapted into episodes. It's been 3 so far with a 4th coming, and it doesn't look like it's going to stop there. I've seen other animes that have adapted movies into 4 episodes miniseries, but not much more than that, and this looks like it's going to continue. On other hand, it's hard to think they can adapt a movie into a whole season. My question is,

Is this adaptation of this Kimetsu no Yaiba movie Mugen Ressha-hen a mini series apart, or is this going to be the second season of the Kimetsu no Yaiba anime?

Answer 1

According to here:

アニプレックスは「鬼滅の刃を多くの人に見てもらうため、竈門炭治郎立志編、遊郭編のそれぞれとつながるエピソードである無限列車編をテレビアニメという形で提供する」と説明。原作のストーリー（立志編→無限列車編→遊郭編）をテレビシリーズだけで追えるようにした。

So yes, Mugen Ressha-hen is remade as part of the 2nd series which consists of Mugen Ressha-hen + Yukaku-hen.

Several sources say (e.g. here) that Mugen Ressha-hen will be 7 episodes, but differ on how many episodes Yukaku-hen will have (13 or more).

Answer 2

Mugen Train Arc of Kimetsu No Yaiba is a part of the second season of KNY. It is the same as the movie but with some additional scenes. This arc will be of 7 episodes as per some sources. And the District Arc will air in December. This arc will be of 10 episodes.

Hope it helps!