OSHIMA took part in the Japan-Korea negotiation which had come to an impasse due to the issues on hold and shokei (form of the letters used in negotiations) problems laid down Japanese-Korea Treaty of Amity.
ここで日朝修好条規日朝間の懸案：書契問題により膠着状態に陥っていた日朝交渉に参画することとなる。