Arata walks into a magic school where half the world has vanished and immediately asks the right questions instead of screaming like an idiot, and that alone separates this from every other harem trying to coast on fanservice. The seven girls actually react to him like a person, not a collection of conquest flags. The mystery of what the Collapse Phenomenon is keeps you watching even when the plot starts to fray, because the hook is good enough that you want answers before you stop caring.

Arata Kasuga's ordinary life shatters when a mysterious event called the Collapse Phenomenon strikes his world and his cousin Hijiri vanishes into another dimension. Desperate to save Hijiri and understand what happened, he enrolls at Biblia Academy, a top-secret school for magic users. There he meets seven girls who rule over the academy, each tied to one of the seven deadly sins and counted among its elite. To take back his world, Arata decides he must gain control over these sins. The result mixes magical action and fantasy with comedy, romance and plenty of ecchi humor.