Having lost their parents in a tragic car accident, the twins resolve to return to the countryside and start life anew at their grandfather's house, the haunt a constant reminder of moments from their past.
Greeting them are childhood friends Nao Yorihime and Akira Amatsume, and newcomer Kazuha Migiwa.
It is a warm welcome, symbolic of the days that should come.
Their peace is merely ephemeral, however, as suppressed emotions, born from vows both newfound and forgotten, start exerting their influence on the twins' new lives.
And deep down, a dark secret, only known to them, begins to unshackle.