Background: The spread of COVID-19 has changed people’s everyday behaviors. The present research aimed to describe the dynamics of changes experienced by Japanese people with varying demographic backgrounds, aiming to reveal how those demographic features mediate the behavior changes caused by the pandemic. While most past studies investigating behavioral change caused by the pandemic used multiple-choice questions about pre-selected behaviors, the present research used a free-response style survey to cover a wide range of behaviors. Methods: 301 Japanese with varying demography took part in an online survey. They firstly wrote down at least five activities they frequently performed before the virus outbreak. After, they did the same about their current life. Results: A total of 1858 answers for the before-condition and 1668 answers were collected and grouped into 19 categories. The appearance rate for each category (the number of items divided by the number of participants) was calculated. Those appearance rates were compared across conditions (before and after the outbreak) and demographic features. Conclusion: Although the pandemic altered most people’s daily behaviors, its impacts were not identical to everyone and were significantly mediated by individual’s demography.