In my review for Demon Slayer - The Movie: Mugen Train, I said that it was "The Evolution of Simplicity", a perfect way to continue upon the foundations on which Season 1 of Demon Slayer was built: The idea of perfecting just one, simple concept. In my eyes, a sequel to that season would have had to add to this concept by fixing issues that plagued it - and I concluded that the movie succeeded at this.
Unfortunately, I do not think of Demon Slayer: Mugen Train Arc quite that favourably; it is a retread of the original movie, which does not add to its content in any meaningful way - in fact, I would argue it makes it worse. Before I go over why, however, I would like to provide the first episode of this batch of seven with it's own small review, as it is the only real additional content to be found, and is actually incredibly good.
Appropriately titled "Flame Hashira Rengoku Kyoujurou", this episode focuses on the fiery swordsman's fight against 'Slasher', a demon terrorising the village in which the 'Infinity Train' can be found. The fights against Slasher are all, unsurprisingly, gorgeous - but most importantly, I was incredibly impressed by the final confrontation between the two, with the shots of Rengoku killing the demon with one blow and elegantly sheathing his sword being intercut seamlessly and rather beautifully with a shot of his father doing the same years ago, which is animated in a stunning black and white colour palette. The scene stuck with me for a while after I saw it, and I consider it another excellent example of Demon Slayer's ability to utilise its soundtrack to the fullest extent.
Unfortunately, that's where my praise for this cour of Demon Slayer ends - the remaining 6 episodes, in my opinion, actually make the movie they're adapting worse. This is primarily because I think this episodic format kills the great pacing that original version of Mugen Train has by leaving the viewer on contrived cliffhangers and subjecting them to incredibly weak opening and ending songs. (Also, as a sidenote, why is it that every anime focusing on a train has that same spinning shot of a train in a railway yard in their opening or ending?)
I could have looked past these pacing issues if Ufotable had fixed any notacable issues with the movie, such as the weird tentacle CGI - but they didn't, and I'm unfortunately left with the conclusion that releasing these 6 episodes was intended solely as a cheap cash grab, which is unfortunate.
Ultimately, while I feel quite strongly about the first episode of Demon Slayer: Mugen Train Arc, I cannot say the same for the other episodes it features - I think they're completely unnecessary, and actively harm the original Mugen Train movie without providing any value to make up for it.