Tokyo has plenty of indoor activities to offer on a rainy day. Here are some of the best things to do:

1. Visit a museum or art gallery: Tokyo has numerous art and culture museums that you can visit on a rainy day. Some popular options include the National Art Center Tokyo, the Tokyo National Museum, and the Mori Art Museum.

2. Go shopping: Tokyo is a shoppers paradise, and there are plenty of shopping malls to visit on a rainy day. Some popular options include Lalaport, Sunshine City, and Shibuya109.

3. Relax in an onsen: There are plenty of hot springs and public baths where you can soak for ¥1,000 or less.

4. Visit a library: Tokyo has some unique libraries, such as the Tama Art University Library and the Musashino Art University Museum & Library.

5. Catch a movie: Tokyo has many cinemas that show both Japanese and international films.

6. Play games at an arcade: Tokyo has some of the best arcades in the world, such as the Sega Joypolis and the Taito Station.

7. Take a cooking class: There are many Japanese cooking classes that you can take, such as the Nihonbashi Gourmet Tour and Sushi Roll Cooking Class.

8. Visit an indoor theme park: Tokyo has several indoor theme parks, such as Joypolis and Legoland Discovery Center.

9. Explore teamLab Borderless: This digital art museum is a must-visit for anyone interested in art and technology.

10. Discover Tokyo Skytree: This 634-meter-tall tower offers stunning views of the city, even on a rainy day.

11. Experience Robot Restaurant: This unique show features robots, dancers, and lasers, and is a must-see for anyone visiting Tokyo.

12. Seek refuge in a café: Tokyo has many cozy cafés where you can relax with a cup of coffee and a good book.

13. Visit Meiji Jingu Shrine: This beautiful shrine is a peaceful oasis in the heart of Tokyo, and is a great place to escape the rain.

14. Go bowling: Tokyo has many bowling alleys where you can have fun with friends and family.

15. Take a visit to outer space in Konica Minolta Planetaria: This planetarium offers a unique and immersive experience that is perfect for a rainy day.

16. Go on a food trip at a depachika: Tokyos department store food halls, known as depachika, offer a wide range of delicacies that are perfect for a rainy day. Some popular options include Shibuya Tokyu Food Show and Ginza Mitsukoshi.