Adarushan no Hanayome

Adarushan no Hanayome summary:

The small country of Adarshan recently conquered a territory of the Castoria Empire. To create an alliance between the two countries and secure new border alignments, the victorious Adarshan general, Alexid Deke Adars (the king’s younger stepbrother), was forced into a political marriage with Castoria’s sixth imperial princess Justinia. But she’s only 10 years old!