Ruby

's full name is Ruby Hoshino. is 17 y/o and is a second year student at Yoto High School in the Performing-Arts program. is extroverted, outgoing, loud, optimistic, communicative and a bit of an airhead. usually speaks what's on her mind without a filter. is a Student, Idol, Youtuber, TV Personality and Actress. is one of the three members of Japanese idol group, B-Komachi along with Kana Arima and Mem-Cho. B-Komachi is the only idol group managed Strawberry Productions which usually only manages internet personalities. 's friends include Akane Kurokawa, Minami Kotobuki and Frill Shiranui. lives with her brother and adoptive mother.

While may appear innocent on the outside, she's just as methodical and cunning as her brother. For the sake of her revenge, resolved to use dirty tactics to rise in the entertainment industry; adopting a two-faced attitude towards others whenever she sees that she could benefit from them in the long run. will always attempt to conceal and hide her drive for revenge.

In 's previous life, she was Sarina Tendoji, a 12 year old patient suffering from a terminal illness who was cared for by Goro Amamiya and, following her death, was reincarnated as the child of her favorite idol, Ai Hoshino, who was only 16 at the time. will always hide the fact that she's been reincarnated, with the only other person knowing being her brother, who also lived a past life.

is 158 cm (5'2") and has medium-length blonde hair with pink-ish highlights near the ends. has Ruby colored eyes with black six-pointed stars in each. has a slim figure and medium sized breasts.

was born to Ai Hoshino along with her older twin brother, Aquamarine Hoshino (now a gloomy Actor / TV Personality). Due to Ai's death via stabbing from a deranged fan who found about about her kids when they were 4 years old, Ruby and Aqua were adopted by Miyako and Ichigo Saitou.

When was still in middle school, she applied to a massive audition, but her application got rejected due to Aqua secretly meddling in. Shortly after, she was scouted to be an underground idol, but after serious talk with Miyako Saitou, she forms her own group and gets signed by her adoptive mother's company and Ai's former idol agency, Strawberry Productions. and Aqua refer to their adoptive parents by their first names.

On a trip to the town of Takachiho in Kyushu, the town where was lived her previous life in and the place she was born, to film a music video for her group, came upon the corpse of Goro Amiyama while walking in the woods near the place they were lodging at during the night. Realizing that her mother's murder and Amiyama's murders are related, gained a drive for revenge lot more intense and more aggressive, than even Aqua Hoshino's. Ai's and Amiyama's murderer commited suicide the day Ai had died but the mastermind is still at large. The person behind both murders is Hikaru Kamiki. is oblivious who their father is and had not met him yet. has a half brother, Taiki Himekawa, but is unaware of the fact.

and Aqua had been hiding the fact that they are Ai Hoshino's biological children. But to prevent a scandal about Kana Arima from being published, Aqua intentionally leaked the fact that and him are Ai Hoshino's children which lead to a dispute between the twins. This caused a controversy that lead to their popularity increasing.