Correspondence from the End of the Universe manga volume 4 features story and art by Menota.

Not long after Marko’s arrival at the Bureau of End Management, a wandering monster robbed him of his heart, guaranteeing that Marko would die when his ten-year mission came to a close. Since then, Marko and his colleagues have been tracking the missing heart—and now, the time has nearly come to restore it to its rightful home!