DMAIC-K: a framework for integrating Toyota Kata into the DMAIC Control phase

Purpose This study aims to propose a framework, called DMAIC-K, which integrates Toyota Kata into the Control phase to sustain Lean Six Sigma (LSS) gains over time. Design/methodology/approach Conducted as action research through a single-case study, Improvement Kata, Coaching Kata and the Storyboard were incorporated into the define, measure, analyze, improve and control (DMAIC) Control phase, converting it into goal-oriented daily plan–do–check–act (PDCA) cycles. The framework was evaluated using electricity consumption time series (2020–2024) with two main indicators: adjusted daily consumption (ADC), normalized for seasonality and occupancy and the energy performance index (EPI). Findings The case study shows that after the Improve phase, the historical average ADC of approximately 18.25 kWh/day (2020–2024) was reduced to 16.87 kWh/day during the Control period (April–August 2025), representing a reduction of 7.59% relative to the historical average. Compared with the matched April–August 2024 reference value of 17.60 kWh/day, this corresponds to a reduction of 4.13%. These results suggest that the DMAIC-K routines may have contributed to stabilizing energy efficiency gains over time. Research limitations/implications As a single-case study, generalizability is limited. Future research should apply the framework across multiple sectors and longitudinal periods to validate results. Practical implications DMAIC-K indicates the potential to serve as a low-cost, behavior-centered control system. It offers managers a concrete way to sustain improvements through bi-weekly Coaching Kata and PDCA experiments linked to critical-to-quality factors. Originality/value The study formalizes a framework integrating Toyota Kata routines into the DMAIC Control phase and describes its operationalization through the adjusted indicators ADC and EPI in a nonindustrial context, contributing to the LSS literature on sustaining improvements.