Natsu e no Tunnel, Sayonara no Deguchi

While Hoshi no Koe is just a short, and natsu e no tunnel is a movie, both have very similar themes.. Both contain: -two friends trying to stay in touch via cell phone messages despite being separated by time differences Hoshi no koe is a bit more sci-fi with the space aspect, while sayonara no deguchi has the vibe/setting of something like your name or any other recent makoto shinkai movie If you liked one, you'll probably like the other! 

-They're both short movies. -They both have amazing animation and music -Both felt sentimental and sad at some point -Both the male MC's love interests are far away from them at the end, except Kaoru found a way to get back to Hanashiro. 

"Natsu e no Tunnel, Sayonara no Deguchi" and "Uchiage Hanabe" are two summer films that share a fair bit in common, both in visuals and storytelling. -they both take place in the summertime in a costal small town in Japan -the protagonists are high school students and have similar personalities and character designs -the plot of both are romances with a supernatural twist involving time-travel -the endings are a bit similar in the two films -they both have awesome ending songs Personally I really liked "Natsu e no Tunnel", and I really didn't like "Uchiage Hanabi", but that's just my opinion. They both give off a similar vibe so if that's your thing you might want to check one or both of them out.  read more 

Both deal with time travel in some ways, they're also similar thematically as well with romance and drama aspects. 

- both take place in the summer - both have drama - both have romance - both have magical gates connected to the past