I Was a Bottom-Tier Bureaucrat for 1,500 Years, and the Demon King Made Me a Minister, Vol. 1 (manga)
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For 1,500 years, Beelzebub has happily taken. it easy as a rank-and-file clerk. But her lazy lifestyle comes to an end when the new demon king suddenly promotes her to minister! Can she adopt the appearance and demeanor expected of the highest demon on the bureaucratic pyramid?