The Japanese Patent Office (JPO) allows divisional applications, but it is important to be cautious of the strict rules concerning deadlines. A divisional application can be filed when amendments to the description, claims or figures of a patent specification are allowed. Further, filing a divisional application is also allowed within 30 days from the issue date of a notice of allowance and within 4 months from the issue date of a final rejection. However, there are some exceptions.
A divisional application cannot be filed if a notice of allowance is issued after a final rejection, either through a pre-trial reexamination or through an examination in which an application was sent back by a trial decision. Also, if a notice of allowance is received after a decision in trial to patent or decision in trial to reject, a divisional application is not allowed. In addition, a divisional application cannot be filed after registration fees have been paid because the application is no longer a pending case of the JPO.
Therefore, we would recommend you to evaluate your need for a divisional application, at the time you are filing an appeal against a final rejection or are paying the registration fees. The Asia Patent Alliance has filed several divisional patent applications, and can answer any questions regarding the procedure that you may have.