SPOILERS DOWN THE PATH; THE DISCUSSION BELOW WILL NOT BE COMPREHENSIVE WITHOUT IT.
TREAD CAREFULLY. YOU'VE BEEN WARNED.
The sequel to one of the most successful anime franchises ever arrives in the form of a feature film after a critically-acclaimed first series! Tanjirō (voiced by Natsuki Hanae) and his pals from the Demon Slayer Corps are onboard Mugen Train to hunt down the ranked demon Enmu (voiced by Daisuke Hirakawa). Their encounter with said demon and the relationship they form with Flame Hashira Rengoku (voiced by Satoshi Hino) is the aim of this feature before officially launching us into Season 2.
The first half of the picture is relatively slow. Nothing much happens except for the fact that we reconvene with our favourite supporting characters like the coward Zenitsu (voiced by Hiro Shimono), the loud Inosuke (voiced by Yoshitsugu Matsuoka) and of course the ever adorable Nezuko (voiced by Akari Kitō)! These new kids acquaint themselves with Flame Hashira Rengoku and they instantly admire him to the heavens, because it's hard not to! During this period, we learn a bit about the five basic element styles and how everything else is derived from these. Tanjirō's search for the flame dance he inherited from his father has no answer either, as of now.
The film gears up once we see the demon's ploy in play as he uses a bunch of kids to send these Demon Slayers into a deep sleep dream; a dream so sweet that they would never know they are in one! We uncover info about Rengoku's past, but most importantly, the kids are present in their dreams to destroy the respective Spirit Core. Once it's revealed how pure Tanjirō's heart and inner self is, you'll love this protagonist even more than you already have! Zenitsu's and Inosuke's dreams and unconscious areas are hilarious by the way! Too bad Zenitsu and Nezuko do not have larger parts to play in this movie.
Once Tanjirō realizes he's in a dream, there's nothing stopping this train ride here on out! The dilemma is impossible as he has to leave his once lost family! His action to cut off his neck to break the dream is powerful, and it recurs time and time again during his battle with Enmu on top of the train! His team-up with Inosuke to penetrate the demon's neck bone that's fused with the train is freaking nerve-wracking! And after a humongous tussle, we reach the desired outcome nevertheless.
But what we didn't foresee to happen is the appearance of an Upper Rank demon known as Akaza (voiced by Akira Ishida) and the battle that ensues between him and Rengoku! What an absolutely riveting sequence that throws every expectation out of the window! To see Rengoku slowly dying as Akaza tempts him to become a demon followed by the former pointing out the difference in values between humans and demons is absolutely immense! This leads to the inevitable death of Rengoku with him finally giving a clue to Tanjirō about the flame dance he asked earlier before passing away. His dying words and comments about Nezuko forms a heartbreaking conclusion, and the wait for Season 2 is further painful now! Last but not least, it goes without saying that the hand-drawn animation is pure ecstasy as is the original score, especially for the action sequences.