Amu Hinomori is shocked to find out Ikuto Tsukiyomi's split personality crisis-the one who adopted her when young, supposedly her father. At DAY he is normal BUT at NIGHT he becomes wildly passionate and dangerous. Amu finds herself in love with NIGHT...

"Everything is going to work out." I whispered to myself. "This is a new beginning." It's Amu's first day at Choshi High when she meets her English teacher, Ikuto. He's every girls dream but is especially off limits to Amu. As relationships form and intimacy heightens, Amu's left to make a decision - a decision that could ultimately change her life, for better or for worse.

When she was little, Amu made a big bet with her older twin brother. After their parents divorced the two of them split, will they remember the bet when they meet again? Or, simply keep the usual bro-sis relationship?