Sponsored by the Dong-a Ilbo, Korea's leading newspaper, the Amateur Kuksu is Korea's leading amateur go tournament. The 46th holding of this event took place on December 15 and 16, 2012, at the Korean Baduk Association building in Seoul. Since the winner becomes the Korean player in the World Amateur Go Championship, it was only appropriate that the field of sixty-four included Kim Chanwoo, the first Korean to win the WAGC (in 1998), and Song Hongsuk, the fifth (in 2010). The field also included recent WAGC runner-ups Lee Hyunjoon and Choi Woosoo, 2012 Korea Prime Minister Cup winner Han Seungjoo, and 2011 KPMC runner-up Yu Byungyong. Kim Chanwoo, who turned in a glittering 10-1 performance in the 2012 National Baduk League, entered the Kuksu ranked 2nd in the senior division of Korea's amateur ranking system, while Song was ranked 13th and Choi Woosoo 2nd in the (stronger) junior division. Choi Woosoo's high rank came partly from winning the Lee Changho Cup in 2012.
The tournament was organized in the same way as the KPMC: six rounds played in two days. A notable loser in the first round was Jeon Junhak, winner of the 2012 Michuhol Cup, runner-up in the Lee Changho Cup, and holder of the number-one junior ranking. His loss came at the hands of Lee Juhyeong (11th junior ranking). Kim Chanwoo and Song Hongsuk also lost, as did Song Junhyup (18th jr), who walked away with most of the honors at the 2012 European Go Congress but now fell to Shin Yoonho (22nd jr).
The second round eliminated some more of Korea's best amateurs. Choi Hyeonjae, a quiet 20-year-old who likes children, who had recorded another 10-1 score in the National Baduk League, and who had beaten Song Hongsuk in round one, proceeded to upset the jovial Lee Hoseung (3rd jr) of pair-go fame. Six weeks before the Kuksu, Lee (this time with Jang Yunjeong) had won the International Amateur Pair Go Championship for a second straight year. Earlier in 2012 he had won his way into the BC Card Cup, LG Cup, and Olleh Cup, professional tournaments that reserve places for amateur participation. Getting these places and the chance to tackle and perhaps topple a big-name pro is a major goal for Korean amateurs, and Lee's triple success was a significant factor in his number-three junior ranking. Park Changmyeong, who had won places in the professional LG, Olleh, Myungin, and Samsung tournaments and was ranked junior 4th, lost to Han Seungjoo. Lee Hyunjoon also bowed out in this round.
The third round saw the depature of Choi Woosoo and Lee Juhyung, so of the contestants ranked in Korea's junior top twenty, only four were left in contention: Yu Byungyong (6th jr), Hong Mujin (8th jr), Kim Myeonghoon (9th jr), and Choi Hyeonjae (16th jr). Hong Mujin and Choi Hyeonjae met each other in the fourth round the next morning, the lower-ranked Choi winning. Kim Myeonghoon survived his game, but Yu was upset by Kim Chiwoo, who won the Cho Namchul Kuksu Cup, a national tournament for children, at age 11 in 2005, and KPMC champion Han Seungjoo was eliminated by Shin Yoonho.
In the semifinal round Kim Chiwoo scored another upset by downing Kim Myeonghoon, but Choi Hyeonjae finally overcame Shin Yoonho, and then won the deciding game with Kim to capture the Kuksu title. Besides earning a shot at becoming the sixth Korean world amateur champion in Sendai next September, Choi took home a prize of 2 million won (close to $2000) and improved his junior ranking from 16th to 7th. And Korea had again demonstrated its ability to stand rankings on their head and produce yet another young new title winner.