Bottled-up emotions...
An everlasting oath...
Heartfelt desires...
An enduring regret...
And a childhood promise.

Yuuto was abandoned by his parents and raised in an orphanage in Britain before a trading merchant by the name of Takakura Yoshiomi adopted him and brought him to Japan.

He could barely speak the language, but he had the support and love of his two new sisters, the cheery yet shy Anzu, and the calm, collected Anri.
During his time in elementary school, he also made new friends: the ingenuous and kind Tsubame, and the ostentatious but guarded Izumi.

They were young and oblivious to love back then. They laughed together, cried together, and nurtured irreplaceable bonds with one another.

Ten years later...

The landscape of the town has changed, and so have they.

Yet some things never do change, no matter how much time passes.

"Do you still remember the promise we made that day?"

Ten years ago, during their childhood, there was another pair of twins that they all played with.
Hekiru and Hikaru reappear and the emotions that have since frozen in time are now rekindled.
This marks the beginning of their resplendent time together, their "Clover Days."

[From NekoNyan]