Finally, I managed to go to Genius Bar, Apple Store Ginza today.
Apple Staff inspected my iPhone and concluded that my phone need to be replaced.
Yeah, I can get a new phone, actually used-new phone.
According to an Apple staff, some parts are reused from phones that sent back for repair/replaced.
I thought I can get a replacement on the spot; however, I have been subscribing Docomo Care (Mobile carrier’s care), not Apple care.
Therefore, I need to call Docomo to ask them to send a replacement by mail.
It will cost me 12,000 yen (USD 120) for repair or replacement and I’m lucky that it will reach me tomorrow.
If I have chosen Apple Care at the time of purchase, I could get it on the spot at Apple Store.
Next time, I should chose Apple Care because any problems with Apple products, it is better to check with Apple Store anyway.
I cannot wait to receive a phone tomorrow.