This piece of music should be called "Day Fantasy".

The following is a relevant introduction to pure music:

Pure music is music that does not include lyrics in the original intention of the composition. This music mode expresses the author's emotions completely with pure and beautiful music, so it is generally called pure music. It has no lyrics, but it can embody the wonderful artistic conception with its own beautiful melody.

However, it should be noted that the concept of pure music is to distinguish music with words from music without words, rather than saying that music with words is "miscellaneous" music. After all, vocal music is also a form of music.

The translation of the name "Pure Music" is based on the habits of Chinese people. To be precise, it is better to translate it into "Untitled Music" or "Untitled Music", and it will not produce "Miscellaneous Music" Such ambiguities. Therefore, "untitled music" without words and "titled music" with words are both called music. There is no distinction between pure and miscellaneous music, and of course there is no "pure music" in the true sense.

The above information refers to Baidu Encyclopedia - Pure Music