Kafka and Himeko were lovers in their youth. It was a beautiful love story, but it didn't end with marriage or something like that. Himeko hadn't seen her ex lover for many years, now she's happily married to Welt Yang, or at least she convinced herself that she is. Everything changed when she accidentally bumped into a woman in a cafe

Oh, sorry...

She looked up at the woman's face and froze. It really was her ex girlfriend, Kafka