Ryosuke Namiki founded the Namiki Manufacturing Company with the financial help of his friend Masao Wada in 1918. Namiki had graduated from the Tokyo Nautical School and had worked as a captain of a merchant ship. So, his life had been closely associated to the sea before embarking on the pen business.
According to Mr. Niikura, the pen in the picture was manufactured in the nineteen-twenties.
It is an eyedropper pen -therefore, an O-shiki (O-式)- with a safety valve, as was common in Japan at the time. Its name is “kai-koku” (海国), Sea Country. These words are written on the nib in Roman characters, and on the barrel in Chinese ideograms.
This nib is a 14 K gold, semiflexible. An overfeed supplies all the ink it might need.
With thanks to Mr. Niikura.