As a fan of That Time I Reincarnated as a Slime, I was excited to go and see this movie. This is not an independent movie from the series. You will need to watch at least the first season to have a better understanding of the plot and characters.
Starting the movie, we are swiftly introduced to some new characters and a new country. We are introduced to Hiiro and his companions who are on their way back to the ogre village but are being hunted by unknown assailants. After a fearsome battle, Hiiro and his campions are left for dead. Queen Towa encounters these wounded warriors and takes them back to her country Raja, where she tries to heal them. However, Hiiro is the only one to survive his wounds. Being indebted to the Queen, Hiiro vows to serve under her command. However, we learn along the way that the Queen and her country are in desperate need of aid. Having mined all the gold in the country has caused the rivers to become polluted and Queen Towa must sacrifice herself to save her kingdom. Needing aid, Hiiro rush to the Forest of Jura in search of Rimuru and Veldora. Encountering Rimuru, the rest of the movie plot unfolds with trickery, betrayal, friendship and mystery.
As I watched the movie, I enjoyed the animation as it was immersive and aesthetically pleasing. The action and magic casting with the dynamic camera movements throughout the film makes it a great watch. There are some sections within the movie that the angles and scenes look a bit off but nothing too serious.
The characters and plot of the movie is simple and easy to follow. We have your ongoing tropes of overpowered main characters battling to save his friends, and the mysterious supernatural being in the background. The movie plays out to be a heartfelt drama in a one-off heroine film. I do appreciate the attempt to connect the past and future of the series within the movie. Overall, if you are a fan of the series or the light novel this is a fun, and entertaining movie to watch.