Technically it's Yahweh, the guy decided to name himself after the christian god. It only ended up as Yhwach thanks to the magic of translating a name from hebrew to german to japanese to english.
Some of the translations write his name as Juha Bach. It is literally pronounced the same way as how I wrote above, it's just a silent J for Juha Bach.
Some of the translations write his name as Juha Bach. It is literally pronounced the same way as how I wrote above, it's just a silent J for Juha Bach.