Once every few decades, the gate to a lost city with untold treasure is opened for a limited time.

Adventurer Ruka has come to the ruins of this city to see what he can see.

But there is a condition: the gate can only be traversed by a young girl.

His quest seemingly over before it begins, Ruka is helped by a mysterious fox spirit.

She lends him the power of a girl… by turning him into one himself!