Heaven's Mail(2004)

Heaven's Mail

Emi has a friend she keep in contact via text messages, Kei. They promised to met in the summer but Kei didn't come. It turns out Kei has actually passed away! So who has been messaging Emi? And at the same time, Emi meets Kazumi who reminds her of Kei. Who exactly is Kazumi?
-- summary by Evil Flowers