Add lemon juice to milk (room temperature) and stir lightly. Let it sit for 15 minutes. It will thicken a little and become yogurt-like. Preheat an oven to 220℃ / 428 F.
Dice cheese into cubes.

Put dry ingredients (whole wheat flour, bread flour, cake flour, and baking soda) in a large bowl and stir well with a whisk. Add salt and stir.

Pour 3/4 of the milk over and use a spatula to fold roughly. Pour the remaining water over dry places, and fold it roughly.

Take it out on your work surface, press it to flatten, and spread the diced cheese over it. Fold the dough and sandwich the cheese, and knead lightly to mix the cheese. Knead it until you don’t see almost any flour left or it comes together. Please don't knead too much.

Lightly flour it (whole wheat flour), and shape it into a ball. Place on a baking sheet lined with parchment paper.
Use a knife to score it deep in an "X" shape. Score it until just before cutting. The scoring is to help heat get into the center of the dough while it bakes.

Lower the oven to 190℃ / 374 F and bake for 45-50 minutes until the center rises well and golden brown.
Transfer it to a rack and cool well.
I recommend slicing it thinly and spreading butter.

The inside of freshly baked is still too soft, so let it cool down and then eat it while it's slightly warm.
Wrap it with plastic wrap to prevent drying after it has cooled completely.
It's better to cover it with plastic wrap and warm it up a little in a microwave if you eat it the next day.