The dichotomy between content knowledge and 21st-century skills ("zest for life" in the Japanese context) has been an issue since the early 2000s in Japan. Recently it has been evident in the demand for a high school-university connection. In spite of such a division, involving apparently incompatible or opposite principles, Japan can integrate such a duality. This can be achieved both top down ("tatemae"), through official policy documents, and through daily cultural practices ("honne") using the common language of the school-based professional learning community (SBPLC) behind the scenes of lesson study. Capable teachers subconsciously already combine curriculum, pedagogy and subject-matter knowledge to recognise and respond to students' learning needs. The authors describe this using the metaphor of "three steps forward, two steps back" to illuminate assessment for learning classroom practices in Japan.