Unnamed Memory, Vol. 6 (manga) — Kuji Furumiya

After all the trouble with Miralys, Oscar and Tinasha continue to spend their promised year together. Their days are fairly peaceful—that is, until a birthday celebration for the king is held at the Farsas royal palace. Guests from surrounding nations come to the castle, but an uninvited visitor appears amid the crowd...and declares that he’s there for Tinasha?!