After swapping brake roater disk and pads, the caliper was left untouched for a while. To improve my brake further, I did overhauling the front calipers.
Original piston installer from Narita Auto: https://narita.official.ec/items/51354602
00:00 Greetings and what to do
00:30 Removing fron brake caliper
01:51 Taking out piston
03:06 Cleaning piston and replace
04:09 Caliper cleaned
04:54 Piston assembled
05:39 How to make the piston installer
06:13 Installing dust boot
07:13 Installing new piston
09:20 Cleaning slide pin
10:24 Putting caliper back in
11:04 Bleeding
11:54 Test drive