7 Call

7 Call (7コール) is a manga series by Natsume Hirose. It was serialized in Margaret.

Plot
I can overcome everything because I love you...

Tsukasa, who lost her boyfriend Mizuki from the car accident one year ago, is living vaguely. Suddenly, there's a text message from Mizuki, who was supposed to be dead, written "I will call you for seven times only beginning tomorrow" and Tsukasa is confused about what he wrote. When the past and the present is connected, sad and kind miracle is going to happen.

Other Sources

 * MyAnimeList