Hoshi wo Ou Kodomo: Agartha no Shounen

Also known as: 星を追う子ども アガルタの少年, Children Who Come from Deep Below, Hoshi wo Ou Kodomo: Agartha no Shonen, Viaje a Agartha, เด็กสาวกับเสียงเพรียกแห่งพิภพเทวา เด็กหนุ่มแห่งอการ์ธา, Les Enfants d'Agartha

by Makoto Shinkai, Asahi Hidaka

A young man named Shin lives with his big brother Shun in an underground place named Agartha. One day, his brother left toward the surface with a cristal and Shin has to follow him and bring back the cristal to Agartha. During his journey, he will meet Asuna, a young girl who lives without her father and Morisaki, a man who has lost his wife.