[8] Yamashita started the season by finishing fourth on the junior level at the 2017 Asian Open Trophy.

In September, she won the bronze medal at 2017 JGP Austria behind Anastasia Tarakanova and Lim Eun-soo.

[8] In August 2018, Yamashita made her senior international debut, winning the bronze medal at the 2018 CS Asian Trophy, behind Lim Eun-soo and Yuna Shiraiwa.

In September, she also won the bronze medal at the 2018 CS Lombardia Trophy, behind Elizaveta Tuktamysheva and Sofia Samodurova.

[10] At the 2019–20 Japanese Championships, Yamashita was fifth in the short program but dropped to eleventh place overall after finishing sixteenth in the free skate.

[13] With the COVID-19 pandemic prompting the ISU to assign the Grand Prix based primarily on geographic location to limit international travel, Yamashita was assigned to compete at the 2020 NHK Trophy as part of a field of Japanese skaters and South Korea's You Young.

[14] In the free skate, Yamashita attempted a quad Salchow in international competition for the first time, landing it with a full downgrade, as well as making errors on two other jumps.

[16] At the 2023–24 Japan Championships, Yamashita unexpectedly placed second in the short program, albeit nearly nine points behind segment leader Kaori Sakamoto.