Door to the Unknown「未知への扉, Michi e no Tobira」 is the 234th chapter of the manga, Nanatsu no Taizai.
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Question Corner
Q245. March Hare-san (From Hyōgo Prefecture): Did Meliodas know about Gowther being a doll?
Nakaba: The original Gowther was one of his best friends, so of course he knows.