Sayori is initially portrayed as the archetype of a Genki Girl, expressing a bubbly and cheery disposition. She is very clumsy, noted for finding ways to accidentally hurt herself or to drop things. Regardless, she is shown to be a jokingly cunning individual who can trick others to get food, shown after managing to eat Natsuki's cookie without her permission. Sayori has also been known to obsess over an activity, only to drop it a few days later, as stated by the protagonist during an interaction between them. This could also be the case with writing poetry, as the protagonist wonders if she might drop it later on, though he also notices that she is a lot more passionate about writing, as she mentions earlier on that it helps her to express and understand her feelings better.

However, it is later revealed that she suffers from bad depression and works so hard to make the people around her happy to cope with her own lack of self-love amongst other things. She is also usually the only character, other than the protagonist, shown to break up arguments, Monika noting that her sentiments are necessary to keep a relaxing atmosphere in the Literature Club (proven by her absence in Act 2). Monika notes that while she may look like a good leader, Sayori is usually better when it comes to dealing with people, notably at mediations. Sayori tries her best to help everyone be happy and dislikes attention directed at her well-being because she feels unworthy of anything that others have to offer her.