Ao no Déraciné

A Japanese-American boy named Shiina Atsushi resides in Japan during World War II when he discovers a Chinese girl lying among the wreckage of a ruined building. She has a glowing mark on her back and says she is from a destroyed alternate world. As she tries to depart, soldiers arrive and insist she accompany them. Questions arise about her true identity and what choices Atsushi will make.