A complex 4-voice canon utilizing the interval of the ascending 6th to drive the harmonic motion. The piece is notable for its dense polyphony and high level of technical control required to keep all lines distinct.
The main challenge is achieving textural clarity while managing the dense, overlapping entries of the four voices.
Comparable difficulty and character — good candidates for what to learn next.
Canon 4-voice ascending 6th in B-flat minor is rated Henle level 5 of 9 — late intermediate repertoire, roughly ABRSM grades 6–7. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 5 — meaning you can already play level 4–5 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Canon 4-voice ascending 6th in B-flat minor lasts about 3 minutes.
Canon 4-voice ascending 6th in B-flat minor is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Canon 4-voice ascending 6th b moll by Jun Yamamoto, Canon 4-voice descending 6th in C minor by Jun Yamamoto, Canon 3-voice in A major by Jun Yamamoto — see the full similar-pieces list on this page.