Sonia and Peko do not interact much, but they seem to be friends. In a secret scene during Chapter 1, Sonia and Peko attend a girls-only gathering event where they bake together. During Chapter 2, Sonia once again holds a girls-only gathering event at the beach, which Peko attends. Before Peko's execution in Chapter 2, after she calls herself a tool for Fuyuhiko Kuzuryu, Sonia denies this profusely, saying that the time they spent together was proof.
In Sonia's Ultimate Talent Development Plan, at the Sports Festival, she is set as the captain of the basketball team. Between the options of what plans will she go with, if the player chooses "offense, offense, offense!", she may choose Peko to be a part of her basketball team, along with Akane Owari. Sonia then yells to both girls, "Sally forth!" Akane doubts herself at first, but quickly becomes frenzied. Peko asks Sonia for answers, after pointing out to Akane that they were playing basketball, not martial arts. Sonia apologizes, claiming that she had always wanted to tell both her and Akane to sally forth. Afterwards, Sonia had set an "unbeatable" offense with the two.
In most fanart, Sonia is shown to be excited to be around Peko, while Peko is trying to follow Sonia and her caring and bubbly personality and energy. Sonia and Peko’s personality’s both are good in a relationship. Sonia has a sweet, caring and nurturing personality. While Peko has a quiet and mysterious personality. These personality’s are good for each other because Peko would want to be with Sonia more because she is nice and caring to Peko, and Sonia would be more nurturing and kind to Peko and like being with and around her.
Since Soniako is a crack ship, the fan base doesn’t make much fanart and attention towards it. But there is still some fan art and Soniako shippers flying around somewhere. Soniako has more popular rival ships such as Sondam and Kuzupeko.
- Peko Protection Squad refers to the ship between the two and Ibuki Mioda.
- Sonpekowari refers to the ship between the two and Akane Owari.