大作 (taisaku) Japanese meaning: large-scale work | KotomoraHis new work is a large-scale work exceeding 1000 pages.
Usage patterns
〈人〉が大作を発表するfor someone to release/publish a large-scale work
The author released a monumental new work after a ten-year gap.
大作に取り組むto work on/tackle a monumental piece
He spent several years working on this monumental piece.
大作を書き上げるto finish writing a large-scale/monumental work
She finally finished writing that monumental work.