Why didn't the Japanese leave Manila during the end of war?

Question:

Why didn't the Japanese soliders leave Manila when they have declared it to be an open city? When you declare a city as open, you try to preserve the buildings, monuments, etc from further damage. But they didn't leave, thus forcing the Americans to siege the city instead of going to street combat.

Isn't that the same as taking a whole city hostage? Has the japs apologized for this one particular incident?

Answer:

I know a lot about this, it is known as the Manila Massacre. However anything I say the Japanese ninjas here will assassinate my answer.

So I will just say that Japanese conduct of war is different to what you think.