Top Seek Let 5 (Kadokawa Tsubasa Bunko)

[Machine Translation] I, Nano, attend a top-secret "spy academy" whose very existence is a secret. During the winter break, we went to Greece, the place where the school began! For our assignment to make a movie introducing the history of the school, we head to the oldest school, which is hidden under the sea. What do you think, we found a "Pandora's Box" that brings disaster! The identity of the traitor and all the truth is revealed. Fate is in a state of flux in the land, and you can never go back to the time before you knew the secret! From elementary school intermediate level.

あたしナノが通うのは、存在自体が極秘の“スパイ学園”。冬休み、そんな学校のはじまりの地・ギリシャにやってきたんだ!「学園の歴史紹介ムービー」をつくる課題のため、海底にしずむ最古の学園に向かうあたしたち。なんと―災いをもたらす『パンドラの箱』、見つけちゃった!!?今巻もヤバさMAX!明かされる裏切り者の正体とすべての真実。かの地で宿命は大きくうごき、あなたももう、秘密を知る前には戻れない!小学中級から。