Naoi Rei's journey to becoming the first Japanese idol under Starship Entertainment began with a concert DVD. Growing up in Nagoya, Aichi Prefecture, the young Rei discovered K-pop through Red Velvet, and one member in particular captured her imagination. "I decided to come to Korea from Japan after seeing the performance of Red Velvet sunbaenim," Rei revealed in a 2022 interview with W Korea. "It's like a dream. I'm happy."1 Joy became not just her bias but her reason for pursuing an entirely new life in a foreign country.

That dream materialized in April 2018 when a 14-year-old Rei auditioned at the Loen Friends Global Audition held in Japan. She performed Red Velvet's "Happiness"—a fitting choice given the group's role in shaping her aspirations.2 Her distinctive vocal tone caught the judges' attention, and within a month of passing, she made the monumental decision to leave her family and move to Seoul.3 At just 14, she became the first Japanese trainee in Starship Entertainment's history.

Arriving in Korea in May 2018, Rei faced the dual challenge of mastering both the language and the rigorous demands of K-pop training. She enrolled at the School of Performing Arts Seoul (SOPA), studying in the Applied Music Department alongside fellow trainees who would eventually become her IVE members.4 During her trainee days, she shared a room with Liz, forming a bond that would carry into their debut years.5

"I auditioned in Japan and a month later, I joined the team," Rei recalled in an interview with Cosmopolitan Korea. "I still can't believe that I've debuted."6 Her Korean improved rapidly through daily conversations with her fellow trainees. "My members call me Kim Rei saying I'm good at Korean," she explained, "but this is honestly all thanks to their help. Since we talk everyday in our dorm, my speech improved right away."6 The nickname "Kim Rei" stuck—an affectionate acknowledgment that this Japanese teenager had become so fluent that she seemed more Korean than foreign.

On November 6, 2021, after three and a half years of training, Starship Entertainment revealed Rei as the fifth member of their upcoming girl group IVE. The announcement positioned her alongside former IZ*ONE members Yujin and Wonyoung, as well as fellow newcomers Gaeul, Liz, and Leeseo.7

The group debuted on December 1, 2021, with the single album "Eleven." During their debut press conference, Rei articulated her vision for the group's sound: "The way the ethereal mood melds with the six voices is how we wish to hook people in."8 The Japan-born member added that she hoped to see IVE become "a group to listen to among the so-called 'MZ generation.'"8 Just one week after debut, the group won their first music show trophy on Show Champion—making them the fastest girl group to achieve this milestone.9

While Rei debuted as IVE's main rapper, her contributions soon extended beyond performance. For the group's breakthrough hit "Love Dive" (April 2022), Rei contributed to the rap lyrics alongside fellow member Gaeul.10 But it was with "After Like" (August 2022) that her songwriting abilities gained wider recognition.

Billboard noted that IVE's "After Like"—which samples Gloria Gaynor's iconic "I Will Survive"—featured "fiery rap verses" with "the lyrics written in collaboration with IVE's very own Rei."11 Speaking about the song's message, Rei explained: "It's a song about expressing your feelings not only with your heart but through your actions as well, and we wanted to confidently and boldly express that in this song."12 The track achieved a "Perfect All-Kill" on Korean charts and won 14 music show trophies.

Her songwriting contributions continued across subsequent releases, including "Hypnosis," "Not Your Girl," and "Next Page." By the time IVE released their first studio album "I've IVE" in April 2023, seven of eleven tracks featured songwriting credits from the members—a testament to how the group, including Rei, had matured as artists.13

Success came at a cost. On April 10, 2023—the very day IVE released their highly anticipated first studio album "I've IVE"—Rei attended the comeback press conference but had to leave after the photo wall session due to her health.14 The following day, Starship Entertainment announced that Rei would temporarily halt all activities.

"Rei recently felt abnormal symptoms such as heart palpitations and stuffiness, so she visited a hospital and received consultation and a checkup," the agency stated. "She received the medical opinion that treatment and stability are needed."14 The news came as a shock to fans who had watched the 19-year-old work tirelessly since debut.

Two days later, Rei posted a handwritten letter to fans on IVE's official fan cafe. "Right now, I'm pausing for a moment to take good care of myself," she wrote. "After becoming a member of IVE, I diligently raced forward hand in hand with the five best members ever... I'm slowly making efforts so that this time doesn't become meaningless."15 Her vulnerability resonated with fans worldwide, who rallied behind the hashtag #GetWellSoonRei.

On May 26, 2023, Starship announced that Rei's symptoms had "improved greatly" and she would resume activities.16 The six-week break had been brief but necessary—a reminder of the physical toll that K-pop's relentless schedule demands.

In a candid 2023 interview with NME, Rei opened up about her personal growth since debut. "In these sixteen months since debut," she reflected, "I'm learning how to love myself and to have confidence in whatever I do, and whatever appearance that I put out there."17 For an artist who moved to a foreign country at 14 and spent years as a trainee before finally debuting, such self-acceptance represented hard-won wisdom.

She also spoke about IVE's place in the competitive landscape of fourth-generation K-pop. "Just being a part of this new generation of strong girl groups is an honour," Rei said. "Each group has different images and charms, and what [they] put out is inspiring, so that we can work harder and show more of our best selves."17 The comment revealed a competitive spirit tempered by genuine appreciation for her peers.

Rei's personality—described by her members as "random" and "goofy"—has made her a memorable variety show guest. Her debut appearance on SBS's "Running Man" in January 2023 showcased her unfiltered honesty: when host Yoo Jae Suk asked about her popularity in school, she replied deadpan, "I didn't have friends."18 The response caught the veteran MC off guard and endeared her to viewers.

She returned to "Running Man" in May 2024 with Yujin, participating in a hilarious episode where she "bickered" with Yoo Jae Suk throughout the filming.19 Her straightforward personality and unexpected responses have become a trademark, with members noting that she "often says things that hit the nail on the head."6

In December 2022, Rei achieved a significant milestone in the fashion industry: she became only the second K-pop idol—after BLACKPINK's Lisa—to grace the cover of Vogue Japan.20 The achievement highlighted her growing appeal in her home country and cemented her status as a Gen-Z fashion icon, with her distinctive "Hime cut" hairstyle and anime-like visuals drawing particular attention.

Her fashion recognition extended to brand partnerships with Korean beauty and lifestyle brands including Bonajour, FCMM, and Peach C, all of which named her as a brand muse in 2022. She has also appeared in pictorials for Arena magazine (2022) and Cosmopolitan Korea (2023), further establishing her dual identity as both performer and fashion figure.

When asked about her role in IVE, Rei articulated a poetic vision: "As the only foreign member, I want to become someone like IVE's rainbow. A member who helps her team shine through various colors."6 The metaphor captures the unique position she occupies—a Japanese artist in a Korean group, bringing a different perspective while integrating seamlessly with her members.

Years after moving to Seoul as a 14-year-old with a dream sparked by Red Velvet, Rei has evolved from a hopeful trainee into a songwriter, fashion icon, and one of K-pop's most distinctive rappers. She finally met her bias Joy, eventually forming a real friendship—drawing a portrait of her idol and exchanging pleasantries at a shop they both frequented.1 For Rei, the dream that began with a concert DVD has become a reality far beyond what that young girl in Nagoya could have imagined.