Actually a subversion - Sigma's mind is 22, but many thanks to Mental Time Travel he is in his 67-year-old system, and spends about 99% of the game entirely unaware of this. Not to mention that by looking at the counter on the game shop in the Watanagashi Arc, Yu-Gi-Oh! School Club Front: The main forged generally use their Game club for other purposes at the time the Hate Plague sets in.