How a Realist Hero Rebuilt the Kingdom (Light Novel) Vol. 13

BATTLE AT SEA
Risking her life to save her homeland, Shabon, a princess from the Nine-Headed Dragon Archipelago, joins Souma’s side in hopes of stopping an impending war. But with a fleet already en route to the hostile archipelago under his orders, Souma sets out on an infiltration mission before it arrives, and he discovers that the real threat is a massive creature in their waters that defies all common sense!