Regarding No. 15 of the form for “Application for Extension of Period of Stay”
In No. 15 of the form (It can be found here.), you have to answer “yes” or “no” to a question whether you have a “Criminal record (in Japan / overseas).” In Japanese, it is stated “whether you have been subject to any action or measure due to a crime.”
If you are sentenced to pay any fine or to any imprisonment (including a suspended sentence), you have to state “yes” with this question. For example, if you are ordered to pay fine for a traffic violation, you have a criminal record.
If you are arrested but have not been prosecuted, you can state “no” with this question.
If you have to fill out “yes” with this question, it is better that you add as an attachment a statement with your signature describing how you are sorry for the criminal case.
Don’t ever try to write false statement in the form. The immigration office has criminal database on its own which is updated by the authorities. If any statement is found to be untrue, it is recorded that you have filled out false statement and it will make your application very unlikely ever to be successful in the future.