In early September 2022, Shimada made her ISU Junior Grand Prix debut at the event in Ostrava, Czech Republic.
[8] At her second Junior Grand Prix assignment in Gdańsk, Poland, Shimada scored 68.81 in the short program after landing her jump combination on a quarter.
[12] In the free skate, she stepped out of her triple Axel and underrotated her quad attempt, but was first in that segment as well, winning the gold medal with an overall margin of 5.22 points over Shin.
[17] At the World Junior Championships in Calgary, Shimada finished first in the short program with a new personal best, 0.59 points ahead of Shin in second place.
[18] Two days later in the free skate, Shimada landed both her triple axel and quadruple toe loop, although the latter jump was completed on the quarter.
She then skated the rest of her program cleanly, receiving another personal best of 152.76, winning the event with the fifth highest score ever recorded by a junior woman.
The program was inspired by the Mexican folktale "La Carambada," with Shimada portraying a female thief that steals from the rich and gives to the poor.
Additionally, Canadian violinist, Judy Kang, who has previously worked and performed with Lady Gaga, helped arrange the music specifically for Shimada.
[22][23] Prior to the season starting, Shimada said that in addition to defending her titles from the previous year, her goals included winning the 2024 Winter Youth Olympics.
[24] Shimada began the Junior Grand Prix on home soil, with Osaka playing host to the 2023 JGP Japan.
[25] She went on to win another gold medal at the 2023 JGP Armenia, posting a 33-point margin over American silver medalist Elyce Lin-Gracey, her only error again being a fall on her quad toe loop attempt.
[27] She unexpectedly placed fourth in the short program after failing to complete her jump combination, which she attributed to nervousness because of her desire to qualify to attend the Youth Olympics and the World Junior Championships.
[28] She rallied in the free skate, where she fell on her quad attempt but landed eight clean triple jumps, finishing twelve points ahead silver medalist Ikura Kushida.
She joined Shizuka Arakawa and Miki Ando as the only women to win three consecutive national junior titles, saying "I wonder if I got closer to the two of them.
[30] At the 2023–24 Junior Grand Prix Final, Shimada came second in the short program, behind primary rival Shin Ji-a, after an error on the landing of her triple Lutz.
"[37] Shimada concluded the season at the 2024 World Junior Championships in Taipei, in another presumed contest with Shin for the gold medal.
She finished second in the short program, 0.88 points back of Shin, after her triple flip received an incorrect edge call.
Upon discovering the song, "Mado Kara Mieru," Nichol suggested that Shimada use this music to represent the four seasons of Japan, starting and ending with spring.
[42] On the Junior Grand Prix, Shimada claimed victory at the 2024 JGP Latvia, winning by a wide margin despite errors on her quad toe loop and triple Axel.
[45][46] In late November, Shimada competed at the 2024–25 Japan Junior Championships, where she won the national title for a fourth consecutive time.
"[50] Two weeks later, at the 2024–25 Japan Championships, Shimada won the silver medal behind Kaori Sakamoto after placing second in both the short and free program segments.