This is the story of Ai, an introverted girl who's struggling with her best friend's suicide. Her fate is forever changed when she acquires a mysterious "Wonder Egg" from a deserted arcade. But all is not what it seems.

Every year, the Yokoyama clan gets together to honor the life of eldest son Junpei, drowned 15 years earlier while saving a man from drowning. Retired physician father Shohei still mourns, while his wife Toshiko has become a passive-aggressive domestic goddess, the two bicker continually. Surviving son Ryota has married at last-his new wife Yukari is a widow with a young son. Daughter Chinami and her car-salesman husband have their two kids in tow....

When Hinako moves to attend university, she falls in love with Minato, a firefighter, but when tragedy strikes, Hinako finds she can still depend on Minato in unexpected ways.