Display omitted •Precision masses of exotic nuclei define the r-process pathway.•A new storage-ring mass spectrometry is proposed.•Individual injection method with the fragment separator is invented.•Cyclotron-type isochronous storage ring is designed.•RI beam science will be expanded at RIBF. Nuclear mass is of fundamental importance, reflecting a variety of structures and interactions formed by constituent nucleons embedded in the nucleus. Precision masses of extremely neutron-rich nuclei define the pathway of r-process nucleosynthesis. The identification of the r-process is one of the unanswered questions in physics in this century. A related challenge is to measure the masses of such short-lived rare isotopes with extremely low production rates. In conjunction with high-energy and high-intensity exotic RI beams available at the RIKEN RI Beam Factory, a new type of storage-ring mass spectrometry is being developed. The novel idea of a cyclotron-like storage ring coupled with an individual injection scheme is introduced in isochronous mass spectrometry.