This is a spectacular event that you’ll have to see for yourself to feel the atmosphere. Thousands of LED dome-shaped lights resembling hotaru, or fireflies, are set floating down the river, and with Tokyo Skytree in the background, it is a night that anyone would remember. The Tokyo Hotaru Festival started in 2012, and due to overwhelming popularity it was held again this year on May 25. For a night, the Milky Way can be seen on Earth at the Sumida River in Asakusa.