This study aimed to qualitatively explore employees’ office use to select physical workspaces in their flexible office environments and their changes after teleworking accelerated by COVID-19. We conducted a research diary method of 17 employees for a private company in Japan, followed by a semistructured interview of 8 employees among the respondents to investigate their thinking processes and job characteristics behind them. The second research diary also examined changes in the employees’ working style and office use after increased teleworking in organizations. Through these steps, we found the following main hypotheses. Although flexible offices are often discussed in terms of the ability to select places to work flexibly, the present study identified certain restrictions due to job characteristics that can limit this flexibility and increase employees’ awareness of these constraints. To maximize the benefits of the limited flexibility, employees proactively select places to work or arrange their time inside or outside of the office, taking into consideration job characteristics, and reevaluate their job and roles. As a result, they engage in diverse job crafting. This crafting could solve a trade-off between concentration and communication. Even if employees recognize constraints in concentration or communication, the trade-off could not occur owing to encouraging devising as job crafting.