Cow Room Escape is a significantly more difficult room escape game than its hard-shelled brother. For this game's ultimate combo-lock puzzle, you're looking for several different colored coins and you will really have to use your wits if you are to find them all.
There are a couple more difficult pixel hunts that are present in this one, so if you're one that is easily turned off by this, then you might want to try a different one. In particular, there is a spot on part of the tall cabinet where you will need to get one item from. Knowing that should hopefully get you by. Again, the descriptions are entirely in Japanese, and this may tend to make the game a bit more difficult than necessary.
Remember to use all the resources available to you, and that some things may be dirty and require a good cleaning.