It’s just milk (a little over 5oz, about 150ml). If the heat is relatively high, it thickens up quite quickly. Usually a Doria would have a white sauce, perhaps thickened with flour, or a tomato sauce. The ketchup/stock granules/oyster sauce mixed with the milk makes it unnecessary to add flour.
Here’s a machine translation of the ingredients:
[10 minute Doria * amounts]
(For 2 people)
Butter 10g
Bacon 40g
1/2 onion
Broccoli 1/2 share
Ketchup 3 tbsp
Consomme 1/2 teaspoon
Oyster sauce 1 teaspoon
Black pepper a little
Milk 150cc
Rice for 2 bowls (careful not to add too much, the rice soaks up the sauce, you want it to be moist at the end, not a brick)

Plenty of cheese
Bread crumbs 4 tbsp (2 tbsp each)
Butter 10g (5g each)