I couldn't wait for a clean release of ep 19's insert song, so I dug through some Youtube comments and NicoNico for some unofficial lyrics and then romanized them. Please take these with a grain of salt, since there's a lot of other noises going on for a good portion of the song. It also seems that some of these lyrics refer to what has been said about Tanjirou, such as Zenitsu describing his voice as "so soft it makes me want to cry".