The aim of this study is to design the peace education unit, which support the students to achieve the two goals: (1) to reconstruct their own notions of peace, and (2) to acquire interdisciplinary concepts and apply them to find and describe the (non-)peaceful situations in our usual life. Therefore, we developed and implemented a concept based inquiry unit (18 class hours) at Hiroshima Global Academy (HiGA) middle school by contextualize the previous unit plan into the integrated learning program on “Global Justice.” As a result, we could choose the six concepts explaining a nonviolent but threatening the peaceful governance, human relation, and agency, demonstrate the social examples to apply them, and set a controversy defining the criteria of peace. The first outcome of this study is that we show the curricular-instructional gatekeeping adjusting to the school context of HiGA. The second is to find the relations between the students' learning of peace concepts and the reconstruction of peace notion.