Finally, the day arrived when Yui, now 20 years old, was selected to debut as a member of a new J-Pop group called . Alongside four other talented members, she took the stage at Tokyo's iconic Shibuya Ota City Hall , marking the beginning of her journey as a professional idol.

After completing her high school education, Yui decided to take a chance and audition for a talent agency that specialized in training aspiring J-Pop idols. The agency, known as , was renowned for launching the careers of some of Japan's most successful music groups.

As Yui navigated the complex world of Japanese entertainment, she discovered the significance of (outside self) and "tatemae" (inside self), concepts that are deeply ingrained in Japanese culture. She learned to balance her public persona with her private life, maintaining a sense of authenticity while still meeting the expectations of her fans and the industry.

For the next two years, Yui honed her skills in singing, dancing, acting, and languages. She trained alongside other aspiring idols, forming close bonds with her fellow trainees. Under the guidance of experienced instructors, she mastered the art of performing in front of large crowds, perfected her stage presence, and developed a charming on-screen persona.