The strange chord in “Ditto” by NewJeans?

It’s E7 with fifth flattened, which is notated as E7(-5). The chord website probably simplified the chords for ease of playing, which is kinda common practice.

By flatting fifth, the note B becomes B♭—In solfa, Re becomes Re♭. Theoretically it strengthens the pull toward the tonal center. And, of course, being a note outside the key, this also provide an intriguing ear-catching stimulus.

Such chords are called “altered dominants”, explained in the chapter V of Chord edition, though not translated yet.

• This reply was modified 9 months, 2 weeks ago by Amachan.

Sonni :

So V7 is casually exchanged to V7(-5)?

Basically yes. But as the note Re♭ prompts resolution to Do, I think it’s good to make it progress to the I chord.

One extra note: For melody you should avoid using natural Re as it conflicts with Re♭, but Ditto is a rare case where the melody sometimes hits Re while the chord plays Re♭, for whatever reason, maybe to keep the melody line natural.