
Samsung Galaxy S5 (Japan/AU KDDI)
Every official firmware build for SCL23, newest first: one row per build with all regions (CSC) that received it.
You can find the firmware on the model: SCL23 page.
Yes, all firmware files for SCL23 are 100% official, original, and obtained directly from Samsung servers.
To flash SCL23, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SCL23.