As my flight was at 6:30pm, I have half a day of free time to explore Tokyo.
Since my hotel was in the Ueno area, I might as well explore the surroundings.

Initially I wanted to go to the Ueno Zoo, but as I've reached the gate, I have decided not to go in, as it's still school holiday right now, and it seems crowded. The Ueno Zoo is actually inside the Ueno Park, so I just ended up wandering around the park.

Now, the Ueno Park is one of the biggest and most visited park in Japan. It's not just a park. Not only it's got a zoo in it, but it's also got a few museums and shrines you could visit, and it's all within the park! 

On the weekends, there will also be different culture performances in nearly every corner of the park. So next time if you're in town, and wanted to do something other than shopping, visiting the Ueno park may be a good option for you. And the best part it, it's all free!

Useful Links:
http://www.japan-guide.com/e/e3019.html
http://www.japan-talk.com/jt/new/ueno-park-in-tokyo
https://www.jnto.go.jp/eng/spot/gardens/uenoonshikoenpark.html