Oripathy, an incurable disease that slowly crystallizes the bodies of those infected until their deaths. Rhodes Island is a pharmaceutical company that endeavors to find a cure and solve the problems that follow in the disease's wake, and in an attempt to put a stop to the revolt of the terrorist organization known as Reunion Movement whose ultimate goal is the salvation of the Infected, Rhodes Island has formed a contract with the Yanese city of Lungmen and continues its mission there. However, Amiya has found herself despondent since their battle against Skullshatterer, unable to accept the fact they were unable to save Misha. In the meantime, Rhodes Island deploys a reconnaissance squad to an abandoned city discovered in the Lungmen countryside. There, the squad notices a strange phenomenon unfolding before them…

 AnimeRulz is the best site to watch Arknights: Perish in Frost SUB and DUB in HD quality.