In order to celebrate the release of Weathering With You in cinemas, not to mention the procurement of the manga license by Vertical, Kodansha have set up a 50% off sale for 4 of Makoto Shinkai's manga adaptations.
The sale covers the following —5 Centimeters per Second, Voices of a Distant Star, The Garden of Words, and She and Her Cat.
For UK fans, check out Comixology UK. I can personally recommend She and Her Cat, which I reviewed for UK Anime Network where it scored an extremely rare 10/10.