Count Sheldon has a collection of dolls that he admires and obsesses over a great deal. The count is often seen carrying his favorite doll, Fiona (フィオナ), a blonde bisque doll dressed up in a Victorian outfit, which Dark Yugi finds creepy.
Count Sheldon disguises one of his dolls as the school nurse. Through this doll, Sheldon defeats Yugi Mutou in a Magic & Wizards game, taking his "Neon Knight" as a reward. Later, Seto kidnaps Yugi, while he is in the arcade looking for a new game called "KIS", so Yugi could face Count Sheldon again. During the Duel, Dark Yugi's monsters had difficulty destroying Sheldon's monsters, even when they had an advantage. Yugi was able to deduce that their presence in Sheldon's "doll house" was giving all of his monsters doll bodies that were harder to destroy: dubbing the effect "doll field." Yugi is able to defeat Sheldon by using the howl attack of his "Death Wolf" to destroy the dolls indirectly. Dark Yugi does not directly places a Penalty Game on Sheldon. However, after the Duel, the count wanders aimlessly in the rain outside of his manor, clutching Fiona, whose face has been cracked.