#io roman degree
A chromatic passing diminished chord on the raised tonic — it links I to ii by sliding a voice up a half step. A colour of transit, not of rest.
Where it lives
1semitones from the tonic
Major mode
diminished
Hear it in context: I-#io-ii-V
Piano sound loads on first tap. Resolved in the key of C — every chord links to its full analysis.