Phase One: The Beginning of Admiration and Devotion

In elementary school, she was hailed as a "genius elementary school student" due to her dancing talent. On the eve of her middle school entrance, she happened to watch a live performance video of "Idol Angel," was deeply moved, and decided to support the idol through action.

Phase Two: From Fan to Research Club President

On her first day of school, she founded the "Idol Angel and Wink Angel Research Club" (later renamed the "Idol Pretty Cure Research Club") and appointed herself as president. Shortly after enrollment (Episode 2), she met the protagonists Sakuya Utano and Aokaze Nana, and formally established a friendship with them in Episode 6.

Phase Three: Awakening and Transformation

Shigure Kokoro is a member who awakened later in the team. Although she longed to become a member of the Idol Pretty Cure, she was deeply shocked upon learning the truth about them—fighting against dark monsters and purifying them through concerts—and consequently believed she was unfit to join. It was not until Episode 7, encouraged by Sakuya Utano and Aokaze Nana, that she faced her true feelings and formally transformed into Cure Heartful to fight. However, the video of her debut performance after transformation was also uploaded online without permission by Puriru.

In the early stages of her transformation, she was constrained by a strict sense of hierarchy until she was permitted to address her seniors by their first names, after which she truly opened up and integrated into the team. At the end of Episode 6, she uttered the phrase "Kyunkyun shitemasen" (I am not smitten at all), which was the complete opposite of her catchphrase, highlighting the character's inner struggle and growth.

Phase Four: Family Bonds

Episode 14, "To Mother – A Message from the Heart," delves deeply into her deceased father and family background. Set against the backdrop of Mother's Day, the episode allows viewers a glimpse into the profound bond between her and her mother, Shigure Ai, making the character more three-dimensional and fully realized.

Phase Five: Student Council President Election (Episode 41)

To prevent the "Idol Pretty Cure Research Club" from being abolished by student council presidential candidate Kai Chiyo (voice: Akasaki Chinatsu) under a "results-first principle," Shigure Kokoro resolutely decided to run for student council president. However, during the election campaign, she witnessed firsthand the efforts Chiyo made for the school and its students (such as Chiyo kindly lying to lend her umbrella to Kokoro) and was deeply moved. Ultimately, in her final speech, Kokoro voluntarily withdrew her candidacy for student council president, instead delivering a speech of support for Chiyo, and rediscovered the value and meaning of "supporting others." After Chiyo was elected, she also expressed understanding toward the Idol Pretty Cure Research Club.

Phase Six: Emotional Growth

In Episode 31, Shigure Kokoro begins to tease Zakuri, a fairy who was once an enemy, demonstrating that she has fully integrated into the team and can show a more relaxed side. In an interview, voice actress Takamori Natsumi revealed that the original script for that scene was relatively plain, but based on her accumulated understanding of the character relationships, she improvised with a teasing tone, resulting in the final product showcasing Kokoro's adorable and mischievous side.

Phase Seven: The Future After the Conclusion

Five years after the "Idol Pretty Cure Final Concert," Shigure Kokoro, now an internet influencer, watches Sakuya Utano's concert at Hana Road Stadium together with Nana.