We, iGEM GIFU_TOKAI, focus on mRNA and changing its topological form into circular to create a new method for mass-production of protein in cell-free system this year. In the current research of circular RNA (circRNA) for protein production, expressing tandem-repeated protein was generated by circRNA without a stop codon. It shows circRNA has a potential ability that it can skip the rate-limiting process of the central dogma of molecular biology, binding ribosomes to mRNA. However, with conventional circRNA, functional protein cannot be translated because protein aggregation quickly occurs. Therefore, we decided to use translation-coupling system, which is found in operons of bacteria to produce monomer protein from circRNA. With applying it to circRNA, ribosomes repeat translation-coupling phenomenon in circRNA and are expected to express monomer protein. Our final goal is to produce functional proteins such as antibodies more efficiently and cheaper in cell-free system to provide medicaments consistently.