[2] In 2011, Koyama and his family were forced to evacuate their home and move into temporary housing due to the 2011 Tōhoku earthquake and tsunami.
[11] After graduation, he began working as a systems engineer for Ricoh, a company known for having a strong shogi team, in April 2018.
[18][19] The JSA approved Koyama's application stating that he satisfied the qualifications of the test after winning his September 13 game in the 16th Asahi Cup Open [ja] tournament.
[19] Koyama would play one game a month at either the JSA headquarters in Tokyo or its Kansai Branch Office, and his five opponents (in order) would be Kenshi Tokuda, Reo Okabe, Mikio Kariyama, Tomoki Yokoyama and Akihiro Takada, with the test ending as soon as Koyama won or lost three out of the five games.
[24][26] The JSA announced after the game that Koyama would officially be awarded regular professional status and the rank of 4-dan on April 1, 2023.
[27] Koyama became the twelfth professional overall since the end of World War II and the first who never attended the JSA's apprentice professional school to meet the qualifications for moving out of Free Class play and into Class C2 of Meijin Ranking Tournament play when he defeated Kōji Tanigawa in Round 2 of the 74th NHK TV Shogi Tournament in July 2024.
[31] Koyama received the Tokyo Shogi Reporters' Association (東京将棋記者会 (Tōkyō Shōgi Kisha Kai)) award for 2023.