Triangle Sun's 'Secret Letter' came out on September 9, 2009. With this song being about 5 minutes long, at 4:54, "Secret Letter" by Triangle Sun 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. The track order of this song in Triangle Sun's "Iris" album is number 1 out of 13. In terms of popularity, Secret Letter is currently not that popular. In our opinion, the overall tone is not very danceable and projects negative sounds, such as being sad, depressed, or angry.

Secret Letter テンポ

We consider the tempo marking of Secret Letter by Triangle Sun to be Andante (at a walking pace) because the track has a tempo of 107 テンポ, a half-time of 54テンポ, and a double-time of 214 テンポ. Based on that, the speed of the song's tempo is slow. The time signature for this track is 4/4.

Secret Letter キー

This song has a musical key of B♭ Major. This also means that this song has a camelot key of 6B. So, the perfect camelot match for 6B would be either 6B or 7A. While, 7B can give you a low energy boost. For moderate energy boost, you would use 3B and a high energy boost can either be 8B or 1B. Though, if you want a low energy drop, you should looking for songs with either a camelot key of 6A or 5B will give you a low energy drop, 9B would be a moderate one, and 4B or 11B would be a high energy drop. Lastly, 3A allows you to change the mood.