If you are arrested for a crime in Japan, you will be under detention as a suspect for maximum 23 days. After this detention, the prosecutor will decide to prosecute the case, or decide to drop the case. So, if you want the case to be dropped, you will have to do what you can do, such as apologize and make out-of-court settlement, within these 23 days.
If the prosecutor prosecutes you, your detention is likely to continue until the end of the criminal trial (it could continue for months or maybe years). But after the prosecution, there is a chance for bailment. The bailment money is usually around JPY2,000,000- (the amount depends on many factors such as your income and assets). The judge will not grant bail if he/she thinks that the defendant may run away or destroy the evidence, so it is important to make a prima facie showing that you will not do such things.
Anyway, when you are arrested, you should get professional help, and ONLY attorneys (Bengoshi lawyer in Japanese) can help you in criminal cases. Do not hesitate to call an attorney.
In Japan, arrested person can use a system called “Toban Bengoshi” (Duty Attorney System). You can ask the police officer to call Toban Bengoshi, and an attorney will be sent from the bar association to interview you. However, you cannot designate particular attorney using this system. If you want to consult an English speaking attorney, you will have to find one yourself.