After failing every high-school entrance exam, a boy begins a gap year under the same roof as elite high-school girls, rebuilding both his studies and his daily life in a youthful light novel.

His gap year starts with a joint battle alongside elite high-school girls.

In a world of swords and magic, a sister uses lies and schemes as weapons to reclaim a magic stone, creating a fantasy with strong con-game elements.

Is that sister a saint or a devil?