R.I.P. (either "Rhodes Island Pharmaceuticals" or "Rest In Peace") is a song by the Japanese singer ReoNa (who previously performs Untitled World and Alive (ReoNa)) that acts as the ending theme of Arknights: Perish in Frost.
Trivia[]
Even though R.I.P. was uploaded on all platforms without the credits in the first place, the one on Arknights' official Facebook was partially muted due to "copyright claim", which quickly became a subject of jokes in the community like what happenned to Alive.
Arknights music