[1] He learned how to play shogi from a book his father bought for him when he was first grade elementary school student.
[2] In September 2006, Ikenaga was accepted into the Japan Shogi Association (JSA) apprentice school at the rank of 6-kyū as a student of shogi professional Kenji Kobayashi.
[2] He was promoted to the rank of apprentice professional 3-dan in 2010, and obtained full professional status and the corresponding rank of 4-dan in April 2018 tying for first with Kōhei Hasebe in the 62nd 3-dan League (October 2017 – March 2018) with a record of 14 wins and 4 losses.
[3] In October 2019, Ikenaga defeated apprentice professional 3-dan Shin'ichirō Hattori 2 games to 1 to win the 9th Kakogawa Seiryū Tournament [ja].
[4] In October 2020, Ikenaga defeated apprentice professional 3-dan Yūki Saitō 2 games to none to win the 51st Shinjin-Ō [ja] tournament.