Formulating line-seru conversion and scheduling problem simultaneously.  Trying to fill the gap in the existing literature.  Validating the proposed model with two numerical examples  Figure A. Seru types Purpose:The aim of this study is to propose a mathematical model for the conversion of the assembly line to the seru production system (line-seru conversion) and scheduling problems and also try to fill the gap in the existing literature. Theory and Methods:Companies such as Sony and Canon have developed a Japanese cellular manufacturing system to meet market demands and to distinguish it from the traditional cellular manufacturing system; they have called this production system a seru production system. In this study, a comprehensive literature review has been conducted. In addition, a mathematical model is proposed for line-seru conversion problem and scheduling problem that aims to minimize total tardiness. The proposed model has been solved for small-sized problems and the results are analyzed. Results:To validate the proposed model and show its efficiency and performance, The model has been implemented in the GAMS 24.1.2 modeling language and two numerical examples are solved by using COUENNE solver on a personal computer (Intel (r) Core(TM) i7-7700 HQ 2.8 GHz and 16GB Ram). The computational experiments indicate the efficiency of the proposed model. Conclusion:Among the various innovations of manufacturing systems, the conversion of the conveyor assembly line to seru production system has attracted great attention both in academic studies and production applications in recent years. However, research in this area is still limited. Especially in Turkish researches, the seru production system is very new and this study is the first study on the line-seru conversion problem. The most important contribution of this study is to propose a mathematical model for the line-seru conversion problem. Also, this study can be applied to assembly-based manufacturing companies. In addition, this work can be extended to the hybrid-seru production system. Due to the NP-hard property of this problem, in the continuation of this study, it is planned to develop heuristic or meta-heuristic algorithms to solve large-scale problems in a reasonable time.