Sarina is the only child of the wealthy Kashiwara family. Her parents passed away when she was young. Sarina has a weak constitution that she inherited from her mother. She is very sickly and depends heavily on constant medication. Sarina has spent most of her life in the hospital and at home. She doesn't have much experience of the outside world and of dealing with people.
Kirari is Sarina's best friend. Sarina is attracted to her cheerful and active disposition. Kirari visits Sarina's home often and she is friendly with Sarina's grandfather. Sarina can be rather stubborn and rebellious. Sarina's friends like to dress her up in revealing outfits.
Sarina's father, Kenichi fell in love with a girl named Yasue who had a weak constitution. He was attracted to her love for life. Unfortunately, his father Masatsugu disagreed with his decision. They argued and both sides stubbornly held their ground. Eventually Masatsugu decided to disown Kenichi. Kenichi and Yasue moved to an apartment.
Yasue's health deteriorated after giving birth to Sarina. The cost of the medical bill became too great and Yasue volunteered to work to support the family. 6 months later, Yasue passed away from the stress. Kenichi fell into depression took to alcohol. After 3 days, he committed suicide. Yuji broke into Kenichi's apartment and gave Sarina to the care of Masatsugu. He also took Kenichi's guitar and later gave it to Sarina.
Chapter 1: Anarchy at the School
Sarina revealed that she is able to play the piano and chose to play the guitar.
In the summer, Japan experienced a lot rain. Sarina suggested that they practice at her home while her grandfather is away. Her grandfather would not approve of her inviting guys to her home. Chie suggested that Shikanosuke dress in drag. The house servants supports Sarina's hobby.
Immediately after the performance at the school festival, Masatsugu grabbed Sarina and stormed off. He grounded her.
Chapter 2: Road to Ruin?
During the summer break, Sarina ran away with the band to follow them on the tour. Masatsugu called her on her cell phone and she threw her cell phone away. After their performance at Nagoya, Sarina called her grandfather from a pay phone. He was still in shock.
At Kiyomizu-dera, Sarina revealed that many of her friends and relatives often send her health food. She appreciated their intention but she doesn't believe that it would help her.
After Kirari received the guitar from Satoh, Sarina taught her to play.
On Sarina's path, Kirari suggested traveling south to Kyushu. At Amakusa, they played at the beach and performed for the people there. Later that night, Sarina and Shikanosuke walked along the beach. She explained that she was born with congenital blood disease. She also revealed her feelings for him and explained that she judged him to be a good person based on his disposition towards Kirari.
The next day, one of the guys at the beach suggested that they travel to Okinawa. The band performed on the streets to raise money for the trip. Yuji, Sarina's uncle, tracked them down and offered them part-time jobs at his hotel at Okinawa to fund their travel.
At Okinawa, Shikanosuke made friends with a colleague, Tom. He brought Sarina and Shikanosuke to visit a music club he frequents called Geisya. The band visited the club during the weekend and Kirari revealed that they were a band. The club patrons requested them to play for them. After the duration of their part-time work, Sarina practised with Shikanosuke.
At Geisya, the girls noticed that Shikanosuke attracted a lot of attention from the men there. They offered him beer after beer and he performed drunk. The band then played successfully at the club.
The day after the event, the club owner invited the group for barbecue at an island. The club owner explained that he named the club after Geishas because he was enthralled by the beauty of Japanese women. Sarina requested Shikanosuke's help to collect star grits. She explained that collecting the number of star grits equal to a person's age will bring the person luck.
On the way back to the mainland, Sarina told Shikanosuke about her childhood and the fate of her parents.
Chapter 3: Run This Way
Kirari revealed that Sarina suffered from high fever after returning from the tour. Sarina was moved to her grandfather's hometown of Nagano. Masatsugu refused to allow Shikanosuke to contact Sarina. Shikanosuke then decided to visit her home. Yuji allowed Shikanosuke into the house. Yuji argued that Masatsugu is keeping an iron grip on Sarina. Masatsugu argued that he will allow her freedom once her health improved.
The next day, Shikanosuke discovered Kenichi's room. Saiki explained that Masatsugu still loves his son and requested that Saiki preserved the room. He also requested to keep the room secret from everyone else and claimed that the room is a storage room.
That night, Yuji explained that he supported Shikanosuke's effort to free Sarina but not to marry her. He also revealed that Sarina's guitar used to belong to her father and that it contained a secret that could help his cause.
That night, Saiki revealed that Masatsugu went to bed early and gave Shikanosuke the key to Kenichi's room. Saiki also led Sarina to the room. Shikanosuke revealed the room to Sarina and explained her father's life and her grandfather's effort to keep it secret. He also talked about his family. Sarina blamed herself for her father's fate and reasoned that if she was born healthy they would be living happily.
The following day, Shikanosuke discovered Kenichi's will that was hidden in Sarina's guitar. In it, Kenichi expressed his sincere wish to return to the family. Shikanosuke presented the will to Masatsugu. Masatsugu broke down because he had always suspected that but had been in denial. He then allowed Shikanosuke's relationship with Sarina and apologized for his attitude.
Sarina decided to stay with her grandfather to make up for running away to join the tour. Sarina saw Shikanosuke off at the train station. Shikanosuke returned home and swore to be a better man for Sarina.
After Sarina graduated from high school, she worked as a manager in the Kashiwara business. She was put in charge of several small companies.
Kira Kira: Curtain Call
Five years after the events of Kira Kira, Yui and Yuko requested part-time jobs at one of Sarina's companies via Yuko's connection to her. Sarina revealed that the company that they will be working at is sponsoring Happy Cycle Mania's 5th year anniversary.
Some time later, Sarina, Yui, and Yuko were returning from an on-site assignment and they ran into Shouki. He revealed that Souta had reunited Super Rock'n'Rollers. At Happy Cycle Mania's 5th year anniversary, Sarina ordered Shikanosuke's Second Literature Club band costume and they performed at the event.
Sarina uses a decorated red colored Gibson SG (1961 reissue).