There is a comet that will land soon, apparently it hasn't been seen for so many years..
The story starts with a boy named Tachibana Taki, and a girl named Miyamizu Mitsuha. Taki-Kun lives in Tokyo, where Mitsuha would love to be, mostly because she'd rather be away from all the problems she has. And Mitsuha-Chan lives in a small rural town called Itomori.
When they both woke up, they switched bodies as a dream. Though, whatever one of them did in the body that they went into, actually affects their real-lives.
Taki find's out that a comet will fly over Japan, what he doesn't know is that the comet is going to cause a lot of damage to Itomori, where Mitsuha is from.
They stopped switching bodies. So Taki (original form) went to her town. But then found out she was dead, and has been dead for 3 years.
Later when it was the day when the comet struck, Taki & Mitsuha switched bodies again, and Taki tried helping to save everyone but no one would listen except for Mitsuha's friends. Then, Mitsuha and Taki finally saw each other face to face. When the sunset went down a little, she disappeared. And immediately he forgot her name..
After Taki got out of school, he was going to work while on the Skytrain, he recognized a girl that he has seen before. The girl recognized Taki because she has seen her before too. Then, they went to go look for each other, And then they reunited, etc. And the story ended.