Queen Nai (The Seat Mate) is The Mother's childhood acquaintance. Back in school, the two sat next to each other in science class, having to do projects together. Her title was derived from considering herself as a queen.

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Not much else is known about The Seat Mate other than having passed away later in life. She reunited with The Mother during the latter's search for The Daughter, engaging in a mutual battle in which she lost.