Kimi ni shika kikoenai (2007)

There is not any point in having a mobile telephone if no one would use it to reach you. That is the lot of a schoolgirl who has barely any friends. Walking through the playground she comes across a toy cellular phone. It rings. It is a call from a mute boy on the other side of the country. They can communicate telepathically over long distances. Their relationship progresses while she finds a third person who reaches her using the same method.