Rachel Liang's '情人知己' came out on January 1, 2011. With this song being about 5 minutes long, at 4:31, "情人知己" by Rachel Liang is fairly a long song compared to the average song length. This song does not have an "Explicit" tag, making it safe for all ages. There is only one song in 情人×知己, so we believe that "情人知己" is a single. 情人知己 is below average in popularity right now. Although the overall vibe is very danceable, it does project more negative sounds.
The tempo marking of 情人知己 by Rachel Liang is Adagio (slowly with great expression), since this song has a tempo of 75 テンポ. With that information, we can conclude that the song has a slow tempo. The time signature for this track is 4/4.
This song has a musical key of E♭ Major. This also means that this song has a camelot key of 5B. So, the perfect camelot match for 5B would be either 5B or 6A. While, 6B can give you a low energy boost. For moderate energy boost, you would use 2B and a high energy boost can either be 7B or 12B. Though, if you want a low energy drop, you should looking for songs with either a camelot key of 5A or 4B will give you a low energy drop, 8B would be a moderate one, and 3B or 10B would be a high energy drop. Lastly, 2A allows you to change the mood.