Suhyup Bank (Sh수협은행) is a specialised bank founded by National Federation of Fisheries Cooperatives(수협). For the Japanese, it's similar to JF Bank(JFマリンバンク).
Like NH Nonghyup Bank, they also have the commercial bank(Sh수협은행) and local cooperatives(회원수협) around the country. To know about the differences between those two, see NH농협은행
. If you get information about their account plans from this website, see carefully the 'Account plan of' section on the top right of the page and visit the correct institution.