We reached Nijō Castle at 4:10 PM, thinking it closes at 5 (according to Google Maps), but the last entry was at 4!
There was a counter right outside selling tickets to their night viewing. Since we had no other slots to fit in the castle, we said - why not?
It turned out to be a wonderful experience. The light show at the lake which depicted the castle's story was so nicely done! It only left us wondering how beautiful the gardens and the castle must look during daytime.