The girls star in yet another drama, titled Aikatsu Detectives! The Princess Diamond Incident. As phantom thieves known as the Shadow Stars plot to steal Hime's Princess Diamond, Ako joins Tsubasa, Yuzu, Yozora, and Mahiru as part of an investigation team guarding the diamond at a party. Despite detectives being place everyhere, the diamond gets stolen under everyone's noses, which Tsubasa quickly deduces wasn't the work of the Shadow Stars. As witnesses are questioned, Ako notices that Yuri shouldn't have been able to legibly write a poster after her right hand was injured during the theft, deducing that she is the real thief. Yuri attempts to escape but is thwarted by Ako and Tsubasa, later discovering that the Shadow Stars had manage to steal the diamond from her. Despite this, Ako is praised by Tsubasa for her efforts.
あこが新人けいじ役でしゅつえんしたスペシャルドラマ『アイカツ！刑事（デカ） プリンセスダイヤ事件』がついに放送！あこがちゃくにんしたそうさいっかにとどいたのは、一まいのよこくじょう。それは、三人組の女かいとうシャドウスターズからのものだった。ねらったえものはのがさないというかのじょたちを、今度こそはたいほすると意気ごむけいじたちで――！
