The implementation of Lesson Study (LS) varies considerably across countries and institutions and is still in a phase of adaptation and experimentation. This article explains the result and the process of a school-based initiative endeavor to implement LS at a suburban elementary in Padang, Indonesia. The study involved 13 teachers, the principal and 6 classes of students. The data were collected through observation and interview. They were classified on the basis of three noticeable emerging themes -- teacher collaboration, scaffolding, and reflection. The data were analyzed qualitatively. The results of data analysis reveal a promising improvement in these aspects. Implementing school- support LS increased by weaving the concept into practice helped teachers develop their professionalism gradually. It was obvious that the teachers felt more at ease to work collaboratively when they designed the lesson. This also affected their design which showed more meaningful learning activities and challenging tasks. Then, the teachers improved the way they scaffolded the pupils. The content of reflection and the way the results of reflection were conveyed became better. The principal's support and the teachers' strong willingness to elevate their quality apparently took an important role. In spite of that, there were some challenges in carrying out collaboration, providing appropriate scaffolding, and doing reflection. Changing the teachers' common practice to LS apparently needs some adjustment and time.