Asa Mitaka is the main protagonist of Chainsaw Man Part 2: Academy Saga. She is a high school student who attends Fourth East High School alongside Denji. After getting killed by the Class President who has contracted with the Justice Devil, she revives and becomes the host of the War Fiend, Yoru. She still retains her human personality when Yoru allows her control, making her a rare case of a living Fiend host.
Asa is a quiet and unsociable girl. She dislikes her classmates, frequently wishing they would drop dead and spurning any offers of friendship. She has a very negative outlook on the world, other humans, and Devils, and tends to assume the worst of others. Asa later admits to herself that her mean-spirited attitude towards her peers was a result of jealousy and a lack of belonging. She also suffers from low self-esteem and considers herself to be clumsy. Despite this, Asa can be falsely self-assured and overconfident.
She struggles with trust and fears being alone, yet also fears approaching others because she worries about making mistakes and ending up alone once more. This puts her in a "cognitive dissonance" as she puts it, where she's afraid of both solitude and companionship.
Her moral compass is somewhat artificial, as she is often more worried about the consequences certain actions carry instead of the actions themselves. She doesn't do so because it goes against her morals but because she does not know what is right and wrong and constantly tries to avoid making mistakes.
Asa doesn't cope well with failure or when things don't go her way. Because of past experiences, she is extremely afraid of making mistakes. Once she does make a mistake, however, she usually gets very angry and blames everyone around her except herself.Though after calming down she'll break down in self-deprecating rants.