I was transcribing a jpop song when I came across this chord progression:

Bb | C Bb | Am | F#dim |

C# | C# | C | C |

F#m7b5 | B | E | .....


I think the song changes from D major to D minor in this part, starting from the the first Bb chord. It then changes to E major after the last B chord.

I'm confused about the usage of C#, C and F#m7b5 in the progression. They don't seem to be in the key of Dmaj, Dmin nor Emaj. Furthermore, While the F#m7b5-B-E progression is similar to a II-V-I cadence, I don't understand why the fifth of F#m7b5 has to be flat.

  • what's the song? I'm really interested to hear this snippet in context, proper interesting harmony here!
    – Some_Guy
    Commented Apr 12, 2017 at 12:54
  • The song is Star!! from a Japanese show called Idolmaster, this snippet is taken from 0:48 of the song.
    – James
    Commented Apr 13, 2017 at 9:51

1 Answer 1


The piece definitely begins in D major, then progresses down by consecutive major seconds to reach that B♭ chord to give it a sense of D minor (the Am chord also helps with this).

The second line of your chords, with the C♯ and C, are suggested to me F major (the relative major of D minor). Thus the C♯ chords might better be spelled as D♭, and this system is just a ♭VI--V progression in F. This F never appears, but imagine that last C chord resolving to F, and you'll hear that F major is definitely implied.

That C chord just resolves deceptively to the F♯m7♭5, which is then treated as a ii half-diminished seventh in the key of E, and the final three chords are just a ii--V--I to cadence in E. Normally in the key of E this ii chord would just be F♯m7, but the composer added in a bit of chromaticism and "borrowed" the F♯ chord from E minor, which has a ♭5. We call this "mode mixture," and it's a very common and effective tool.

  • 1
    Great analysis. Just wanted to tack on some "feelingy" stuff to the end of it; the "effect" of using the Fø B7 preps us to hear E minor, so that when the E major comes instead, it sounds very bright; like a picardy third thing. So when OP says "why does the 5 have to be flat", in terms of how the music feels, it means that it makes the E major chord really "pop" in a sense, giving it a kind of "strident" or "bright" sound to it.
    – Some_Guy
    Commented Apr 12, 2017 at 13:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.