Episode 29

The Key (鍵) is the ninth episode of the second season, and the twenty-ninth episode of The Eminence in Shadow anime adaptation.

Synopsis
遺跡に隠された“鍵”を巡る、王妃をも巻き込んだ戦闘が始まる.
 * -|English= On the way to the Kingdom of Oriana, Cid is also on a journey of self-discovery and reflection. He feels like something's missing. Is he imagining it?
 * -|Japanese= 559の下でオリアナ王国の遺跡調査にあたる666たちは、教団幹部に連行される666の母レイナ王妃を発見.

Trivia

 * 664 citing how 559 defeated no.89 is a callback to her cameo in Episode 20, how she defeated a gatekeeper to earn the right to challenge a higher number for rank promotion.
 * The First Children use computer tablets and a key card to access the vaulted item in the ruins. This detail connects back to the memories within Sanctuary from Episode 12 how the present world is a recovering post-apocalyptic society.
 * Cid carries a duffle bag with a ski mask, sweater, and crowbars when he kills three thugs before returning Marie's money. This is a callback to his past life as the Stylish Ruffian Slayer in Japan.