Sick leave and paid holidays are an area of the employment contract where there is a big cultural divide. Just as many westerners can’t fathom that these wouldn’t be in a contract, many Japanese can’t imagine why there would be.
Teachers directly hired under the same contract as their Japanese counterparts may have something like 40 days of paid holiday to be used during the school holiday periods, but the days can also be used as paid sick days during the year if the need arises.
In addition, for teachers on direct hire contracts, there may even be special sick leave called 病休(byokyu) written into the contract. This leave is generally reserved for hospitalisation or severe illness, so if you try to use it for a cold you may have to take a day off using paid holiday instead.
Another option is that you may have all of the summer, winter, and spring holidays off, fully paid, but without a specified number of days to use at will. So if you suddenly come down with the flu mid-year, what are the options?
In most cases, the school will be understanding, especially if it’s something like influenza where you’re being ordered to stay home by the doctor. However, taking time off for colds and headaches is rarer - teachers are expected to just pull through and do their classes regardless of how they feel, and it's the same with students. Note the phenomena of entire homerooms and grades being closed with the flu since sick students and teachers tend to come to class anyway.
If you do take a day off, it is assumed you’re going to the clinic/hospital, so be prepared for your school to ask for a 診断書 (shindansho, doctor’s note). These notes have to be specifically requested and cost an extra fee at the hospital. Just showing your hospital bill or prescription won't count.
Since every school is likely to handle sick leave a little differently, the most important thing is to make sure you clearly understand the school’s policy and what they expect. Some schools are used to the culture difference and make allowances for foreign teachers wanting to stay home and rest. Some think that every teacher should follow the Japanese policy, so not only can you not assume sick leave will be treated like it is in your home country, you can’t assume it will be handled like it was at a previous school either.
For teachers hired through EduCareer, we’re always happy to answer any questions about school policy and help you work with your school!