The Titan's Bride Vol. 5 by ITKZ

LOVE PERSEVERES!Somehow, Kouichi has been pulled into Tildant's succession crisis and is targeted by Tildant nobles, accused of being an unworthy partner to a king. Wanting to protect his beloved Caius and prove himself to the court, Kouichi accepts a challenge to prove his worth once and for all!
Binding: Paperback / softback