What should I do if I don't get to one kilometer after the Kuromi medal?

Keep running badge is a one-time operation. When you signed up for the running medal activity on Keep, you had already selected the established running kilometers and paid the medal deposit. His request is to use your spare time to complete the running kilometers you selected at one time, but there is no limit to the total running time. It doesn't matter if you run for an hour or two.