A general hint.

One of the things  I loved about yume nikki was its very directionless yet intentional game design. I left how to beat the game vague intentionally as to allow people to figure it out on their own. However  I may have left it a bit too vague.  thats on me.  so I will part with one hint that may help. 

as much fun as it is to enter the buildings there is nothing you do in them to progress. both have relatively valuable information from the characters residing  in them but other than that everything you need to do to get Happiness (either ending) is hidden in the main map. you just need to search every corner, which would help if you could see in the dark.