If you are looking at Kawaii/Cute things to do, head to Harajuku!
What to do in Harajuku!
Just explore the entirety of the this street!!! There is so much street food! You can get cute ice cream, lovely crepes, giant cotton candy, and more. There are also places to get stickers, nonsensical English translated T-shirts, makeup, clothes, and more! There are themed cafes on/near this street as well.
Check out this dollar store on Takeshita street! See what nifty things you can bring back home.
Meiji Shrine/Yoyogi Park
Meiji Shrine and Yoyogi park are near Takeshita street. Experience hearing the city to complete sounds of nature as you travel into the shrine or inner park.
This plaza (ometsando harajuku) is another place to shop if you don’t want to buy expensive things at Ginza or Roppongi. Also there are plenty of stores around this area, just walk around.
Before you decide to go to an animal themed cafe, look up locations before heading to Harajuku. Many of these places require reservations: some websites are English friendly where you can book yourself a spot, or there are service areas near Takeshita Street who can book for you!
Kawaii Monster Cafe
If you have plenty of time or just lucky (usually a long waiting line outside), head to Kawaii Monster Cafe! Super cute experience that are photo worthy! Also you can order on a tablet.