Natsuiro no Sunadokei (Hourglass of Summer) is a story about a high school sophomore who has this crush on a girl.
Ok, enough I can't take that type of intro and cliché set-up. What makes me like this story is that it's a bit different from the normal stories that I usually see in anime. What happens is that Koutarou (main character) is going to ask Kaho (female focus) out at the start of summer but the night before he dose he is caught in an odd incident. The result of this is he begins to randomly "Day Drop" which means he suddenly blacks out and wakes up on different days ranging from the start of summer vacation to his first day back to school.
Koutarou first drops to the day of the entrance ceremony after vacation and discovers that he was not only Kaho's boyfriend just yesterday but also that she died in an accident as well. After receiving this shock Koutarou Day drops around in time and tries to prevent the incident from occurring. In the process he changes the future of several people. Also being unable to control the when and where of the Day Drops he builds his relationship with Kaho (even if it is in a very non linear defunct form) and comes to care for her even more because of the situation he lies in.
The ending? Well that depends on how you play the game since your choices can allow her to live or to die.