Houkago wa Koi no Lesson wo / Kimi wa Saikou no Diamond

Mirabelle has fulfilled her childhood dream to marry her first love, an elite teacher named Arthur. But for some reason, her smart and handsome husband refuses to lay a finger on his innocent bride. What secrets from Arthur's past stand in the way of their love? A historical romance double feature set in a beautiful and prestigious school! (Source: Ohzora Shuppan, translated)