I bought a SunDisk‚ĚmicroSDXC anew at Shang-Hi Donya. I checked the speed and it is same as the defective one. I was afraid of the defect but It was no trouble for using one day.
The SunDisk microSDCX that I bought at Amazon Market Place was defective. The microSDXC caused the repetition of mount and unmount. I wanted to replace it for good one but I was able to choose a refund only. I returned it for refund.
Amazon will pay back the amount of SunDisk microSDXC that I returned.
Towards the coming trip, I bought a microSDXC card and headset Bruetooth. Was Mai Kai from Marketplace Amazon's microSDXC because it was hurry.
It was an age and a little cheap 5000 yen in 64GB.
Now, I listen to the music without removing the cover of the earphone jack.