With her jet-black hair, sinister smile, and silent demeanor, Sawako "Sadako" Kuronuma always had trouble fitting in during high school. But with help from her friends, her boyfriend Kazehaya, and even her rival-turned-friend Kurumi, Sawako came out of her shell. Now in college, Sawako and Kurumi have become incredibly close, but Kurumi longs for a romance of her own.

In college, Kurumi thinks she's found her soulmate in Sawako, her rival-turned-best-friend from high school. But Kurumi's feelings for Eiji are only growing. After a fraught encounter with Eiji's former crush, words from Sawako give Kurumi the courage to open her heart and realize who her soulmate really is.