Koga was born in Fukuoka, Japan on February 13, 1996.[1] He learned how to play shogi from his grandfather when he was about four years old.[2][3]
Koga entered the Japan Shogi Association's apprentice school in September 2011 as a protegee of shogi professional Isao Nakata.[2][3] He was promoted to the rank of apprentice professional 3-dan in April 2017 and obtained full professional status and the rank of 4-dan after finishing third in the 67th 3-dan League (April 2020 – September 2020) with a record of 13 wins and 5 losses.[2][3][4][5] Although Koga's third place finish was not sufficient to earn him direct promotion to 4-dan, it was good enough to earn him a second promotion point which gave him the option to enter the professional ranks as a free class player. After consulting with his mentor Nakata, Koga decided he wanted to turn professional even if it meant starting in the Free Class.[2][3][a]
Shogi professional
In September 2021, Koga was promoted to Meijin Class C2 after defeating Hirotaka Kajiura 7-dan to reach the finals of the 52nd Shinjin-Ō [ja] tournament. Koga's victory meant that he satisfied the criteria for promotion to Class C2 for the 80th Meijin League (April 2022 – March 2023).[7][8]
In March 2024, Koga won the 21st Tsume Shogi Solving Competition. He finished with a score of 73 points out of a possible 100 to win the competition for the first time. The tournament had been last held in 2019, but was cancelled from 2020 to 2023 due to the COVID-19 pandemic. Sōta Fujii 8-crown title holder, who won the competition the last five times it was held, did not participate in the competition.[10]
Notes
^Koga earned his first promotion point in third place with a record of 13 wins and 5 losses in the 65th 3-dan League (April 2019 – September 2019).[3][6]
