陥落アルファ　―エニグマ：第4のバース―

"I can't believe that I, an Alpha, am being embraced!" Kuga Tsukasa is the heir to a great company. One day, at a party, he meets a man who appears to be the heir to the Amou empire. Tsukasa intends to use this man for his own gain, but without realizing it he is already underneath him in his bed!