After witnessing the failure of his elder brother Gunji Shigetada’s first Kuril Islands expedition，Koda Rohan was deeply saddened by the Japanese government’s indifference and the people’s shortsightedness. In order to make the Japanese people have a better view of his brother’s ocean exploration activities，Koda Rohan chose to help his brother on the road of literature. Koda Rohan’s earlymaritime ideologies synchronized with that of Gunji Shigetada，and began to have a tendency to advocate overseas expansion. During this period，Koda Rohan promoted the urgency of developing maritime affairs by translating the British marine novel The Great Frozen Sea，but this translation also promoted the retionality colonial expansion to a certain extent. Such war consciousness then reached its peak in the advocacy of marine ideologies by his children’s literature. After the First Sino-Japanese War，Koda Rohan gradually corrected the early extreme marine ideologies through extensive research on marine literature and frequent marine activities，and began to take the development of marine literature as an important part of the revitalization of the ocean country in his creations such as The Billows Dashing to the Skies，and regarded this as a starting point to advocate a diversified path to revitalize the ocean country.