Nagashima earned her bachelor's degree from Cornell University in animal science in 2009 and completed her doctorate in zoology and wildlife conservation in 2015. As part of her doctoral dissertation in the Joint Graduate Training Program (JGTP) between Cornell University and SCBI, Nagashima produced the world's first litter of puppies from in vitro fertilization and cultured domestic dog ovarian follicles using cutting-edge, three-dimensional systems, with the goal of applying these technologies to the conservation of wild canids in the future.