Hakuchizu no Reisende

In a world plagued by dark lands teeming with monsters, mapmaking is the only method that successfully clears the darkness and allows humans to settle new areas. A young pioneer named Zaba meets a beastkin girl named Rita in a cave within the Uncharted Territory. Rita, despite being a slave, possesses the rare ability to quickly create maps using her acute hearing. Zaba suggests joining her on an expedition to explore the abandoned city of Amsterdam, where a possible means to reverse the transformation of humans into monsters is believed to exist.