Togawa Sakiko (豊川 祥子) is a first-year student at Haneoka Girls' High School and the producer, composer and keyboardist for Ave Mujica going by the stage name Oblivionis (オブリビオニス). She is childhood friends with Mutsumi and Uika.

Sakiko was born to mother Mizuho (豊川とがわ 瑞穂みずほ) and father Kiyotsugu (豊川とがわ 清告きよつぐ). She comes from a rich family and currently lives with her father. She used to attend Tsukinomori Girls' Academy. She is a talented pianist who has played the piano ever since she was young.

Sakiko met Mutsumi while they were both in kindergarten. In Uika's case, the two became friends through the Togawa family visiting the island Uika lived at during summers. The two would often go and catch bugs together.

When Sakiko was in middle school, her mother passed away from an illness. While her father swore to do his best to take care of her, he was disowned from the family company by Sakiko's grandfather (Mizuho's father) after taking responsibility of a fraud worth 16.8 billion yen, leading to him moving out into a run-down, small apartment and developing a serious alcohol addiction. Instead of staying with her grandfather, Sakiko moved to her father's apartment and started taking care of him, to the point of having to go and pick him up from the police station frequently after he'd be taken in for misdemeanor or the police finding him passed out in alleyways.

During her 3rd year of middle school, after seeing Morfonica perform at the Tsukinomori Music Festival, Sakiko became a big fan of them and was influenced to create a band of her own. She then had a chance meeting with Tomori. Sakiko composed a song from one of Tomori's notes and then invited her to create a band with her, which led to Sakiko becoming the leader, composer, and keyboardist of CRYCHIC. However, after their first and only live performance, Sakiko became distraught after reading something on her phone, and later told the others that she was leaving the band. Her departure led to the complete dissolution of CRYCHIC.

For high school, Sakiko decided to attend Haneoka Girls' School because the school has a scholarship program.

Sakiko is a generally polite, refined, and reticent girl on the outside. She's overall very secretive, such as trying to avoid Tomori or Soyo's attempts to contact her after CRYCHIC's disbandment, and also keeps her distance from her classmates (as shown when her classmates did not know Sakiko's first name). She appears to be quite ashamed of her current circumstances and is afraid of anyone learning about them, even getting mad at Mutsumi when she suggested that Sakiko start attending Tsukinomori again.

Sakiko also acts cold-blooded towards people she's cut contact with, as shown with her lack of reaction to Soyo breaking down in tears, and ignoring her pleads to bring CRYCHIC back together. She's shown to retroactively frame situations in a way where she appears to take an antagonistic role, regardless of the reality. However, she still feels visceral guilt over these actions.

Prior to the event that changed her and led her down to her current circumstances, Sakiko was shown to be a very cheerful and kind-hearted girl. At her core, she still holds a deep love for her old friends. She's described to be very charismatic, with her very existence "driving people around her mad." She is multitalented, and sensitive to people's emotions as well. Before her change, she had a presence as bright and all-encompassing as the sun.

Sakiko is also shown to love dolls, and when she was a child, she would always take her favorite doll with her when she went to visit Uika at the island during summers.She sat this doll to watch her play the piano. To this day, it remains on display at home.

Her favorite doll used to belong to her mother. After she left her father's apartment, she also brought the doll to Uika's where she stayed temporarily.