Tanaka began skating in 2012 after being inspired by her older brother's classmate, who was a figure skater.[3] She placed fourteenth at 2017–18 Japan Novice A Championships and seventh at 2018–19 Japan Novice A Championships.[4][5]
2019–20 season: Junior Grand Prix debut
Tanaka was assigned to make her Junior Grand Prix debut at the 2019 JGP Lake Placid on the 2019–20 circuit. In her short program, she missed her combination due to a fall and doubled a planned triple Loop, placing her tenth with a score of 51.37 points.[6] During the free skate, Tanaka downgraded four jumps, falling twice, and doubled a Lutz. Tanaka finished in fourteenth place overall.[7] Appearing next at the 2019–20 Japan Junior Championships, Tanaka finished in tenth place.
Tanaka competed at the 2021–22 Japan Junior Championships and placed fifth overall, making her highest placement in the event. She then competed at the senior level, finishing tenth in the short program with a clean skate despite a quarter call on her combination. Tanaka struggled in the free skate, coming nineteenth in the segment and dropping to eighteenth place overall.
Tanaka was assigned to compete at the 2023 Egna Trophy in the junior category. She came third in the short program with a score of 51.35. In the free skate, she under-rotated the first three jumps and struggled on the spins, then finishing in fourth place behind Canada's Fiona Bombardier.[9]
2023–24 season: Switch to ice dance
On 6 May 2023, Japanese ice dancer Shingo Nishiyama announced that he and Tanaka would be forming a new ice dance partnership, and would be training at the Ice Academy of Montreal in Montreal, Canada.[10]
Tanaka/Nishiyama made their international competitive debut on the Challenger circuit at the 2023 CS Golden Spin of Zagreb, coming ninth.[11] They next competed at the 2023–24 Japan Championships, which proved to be a tight contest between them and two other senior teams. Tanaka/Nishiyama won the rhythm dance, finishing ahead of four-time national champions Komatsubara/Koleto and the new team Yoshida/Morita. However, they were third in the free dance, and finished second overall. The team said they were satisfied to have made it onto the podium, noting their rapid progress in the short time since partnering.[12]
^Asano, Yumi (May 6, 2023). "西山真瑚と田中梓沙がアイスダンスでカップル結成、拠点はカナダ・モントリオール" [Shingo Nishiyama and Azusa Tanaka form an ice dance team, based in Montreal, Canada]. 4years Asahi.