Prologue: Childhood[]
As Sarina, Ruby was a big fan of her now mother, Ai Hoshino. She wanted to be reincarnated as her daughter and have a face like her. With due time, her wish gets fulfilled as she is born as Aqua's younger twin. However, only a few years after that, a crazed fan takes her mother's life, and Ruby loses the idol she treasured both in her previous and current lives.
Entertainment World[]
After Ai's death, Ruby starts working hard towards her goal, striving to become an idol like her mom. When she was still in middle school, she applied to a massive audition, but her application got rejected due to Aqua secretly meddling. Shortly after, she was scouted to be an underground idol, but after a serious talk with Miyako, she formed her own group. She gets signed by her adoptive mother's company and Ai's former idol agency, Ichigo Production, Inc. Ruby is then joined by Kana Arima, whom Aqua asked to join to make Ruby's dream come true.
Dating Reality Show[]
Ruby and Kana were featured on a video by the Youtuber managed by Ichigo Production, Inc, Pieyon. After a grueling workout session, Pieyon asks them both about their idol group's name. Ruby named the group after her departed mother's idol group, B-Komachi.
The First Concert[]
Ruby makes a Youtube channel where she and her group uploads videos with the help of B-Komachi's new member Memcho, a renowned Youtuber. They hit the milestone of 10,000 subscribers there. Later, they receive an offer from one of her brother, Aqua's acquaintances, to participate in one of the biggest idol concerts in the country, the Japan Idol Festival. Even though Kana, another member of her idol group, disagrees with the idea of newcomers debuting in such a prestigious event, Ruby and Memcho convince her to accept the invitation. Hence, the revived B-Komachi delivered their first performance on the grand stage, earning rave reviews from fans.
2.5D Stage Play[]
Ruby tries to visit Aqua during his rehearsal for the stage adaptation of Tokyo Blade, but doesn't manage to meet him, learning that he has left early to go someplace else. Later, she appeared on the opening night of Tokyo Blade, watching the performance along with Miyako.