Oyasumi, Nini-chan.

In so much anguish that he couldn't sleep, Ameta thought in desperation that it might be better to end it all. Just as he was about to cast himself off, an angel suddenly dove from the sky and collided with his head. And so begins the heartwarming life of a young man named Ameta and his self-proclaimed angel.

(Source: Shueisha, translated)