The No 3 seeds defeated Japanese Gengo Kikuchi and Shunrou Takeshima 6-2, 7-6 in the first round.
They will play wildcard pair Yuhei Kono and Yuto Sakai of the hosts in the next round.
In another match yesterday, Japanese Takuto Niki and Kaito Uesugi caused an upset by beating No 1 duo Gao Xin and Li Zhe of China 7-6, 3-6, 10-3.
Earlier, Sho Katayama and Arata Onozawa of Japan beat Chinese Taipei’s Huang Liang-chi and Lin Wei-de 6-2, 6-4.
In the singles event, no surprises as all high seeded players qualified for the next round.
No 1 Chinese Li Zhe easily won 6-1, 6-1 over Thailand’s Pol Wattanakul, while No 2 Max Purcell of Australia struggled but beat Sho Shimabukuro 2-6, 6-2, 6-4.
No 3 Takuto Niki beat his Japanese countryman Yunosuke Takana 6-4, 6-4.
Nam will play his second round singles match today against qualifier Lee Jea-moon of the Republic of Korea who defeated No 8 seed Jumpei Yamasaki 6-1, 6-3 on March 13.