Pretty Poison(2006)

Dokuyaku to Otome

Riyako's dream of a happy marriage is shattered when her 'true love' cheats on her. Heartbroken, she finds herself seduced by the beautiful young Shougo, ending in a night of heated passion. However, what seemed like a spontaneous act turns out to be much more as Shougo and her ex-lover are somehow connected! In her confusion, Riyako can't help becoming more addicted to the seductive poison that knows just what buttons to push to convey innocence or evil (and sometimes, both), and a suspenseful and dangerous love affair ensues.