This study seeks to explore the use of cross-platform mind-mapping software by undergraduate students and the factors that influence their choice of devices and time when using mind-mapping techniques as a pre-writing strategy to improve their academic writing skills. The participants of the study were 71 Japanese first-year students in three classes who were taught about computer-assisted and mobile-assisted and traditional mind mapping techniques embedded in their digital devices and textbook for fifteen weeks. This mixed-methods research employed pre- and post-treatment surveys, along with focus group interviews as research instruments. The findings suggest that students made informed decisions about their device choices and technical training time based on their learning styles, technology affordances, pre-writing strategies, and application fees, which had diverse impacts on their motivation and engagement.