I'm a big Kimetsu no Yaiba fan and this movie was really great, really special. However, the second demon that showed up at the end did feel really random. They never stated any particular reason why he was there or looking for them. Like someone else mentioned, there could have been some more foreshadowing or development happening to indicate he was coming to fight them. The other thing I didn't like was all the crying at the end by Tanjiro. I felt like some of that dragged on a bit too long. Other than that, the visuals and story and everything else was great, with the expected Kimetsu no Yaiba quality.