Definition
The person responsible for the end-to-end results of a value stream from order receipt to delivery, with planning, procurement, production, quality, and other functions aligned to him; organizing by value stream rather than by function is the organizational prerequisite for deploying the management system. From a publicly published work, not textbook measurement definition.
In detail
In a functional organization, no one is responsible for the whole "from order to delivery," each stage is locally optimized, yet overall waiting and inventory remain high. The value stream leader carries delivery, quality, inventory, and efficiency metrics for this chain on one person and reports trends weekly to the top leader. The book emphasizes the quality of the chosen person, who need not have a manufacturing background. There is disagreement on when to adjust the organization: some argue for restructuring before the first Kaizen activity, while others argue for piloting first and then rolling out.
Example in practice
A production line was originally managed separately by four departments: planning, procurement, the workshop, and quality inspection, with a delivery lead time of twenty days. The company appointed a value stream leader, assigned the planner and quality inspector under him, and made him report delivery and inventory metrics weekly to the general manager; after three months, cross-departmental finger-pointing decreased markedly, and Kaizen week topics had a clear sponsor.