Junpei Yoshino

Junpei is quiet, intelligent, sensitive, cynical, and deeply affected by sustained bullying. He becomes distrustful of moral language when people who claim to value kindness ignore or participate in cruelty.

Movies are one of his primary refuges. He follows film closely enough to engage Yuuji in detailed conversations about directors, horror films, and the difference between enjoying fictional violence and wanting real people to suffer.

Junpei is not naturally cruel. Even after meeting Mahito, much of his anger remains focused on specific people who mistreated him rather than humanity as a whole.

His friendship with Yuuji Itadori develops quickly because Yuuji interacts with him without pity or judgment. The relaxed evening Yuuji spends with Junpei and his mother gives Junpei a brief experience of friendship separate from manipulation.

Mahito alters Junpei's brain to make him capable of using cursed energy and a shikigami technique.

Junpei's shikigami is Moon Dregs, a large jellyfish-like entity composed of cursed energy. It can surround Junpei defensively, attack with tendrils, restrain targets, and deliver poison.

Junpei can manipulate the poison secreted through Moon Dregs' tentacles, using cursed energy to alter its strength and effects. This allows him to incapacitate enemies without necessarily relying on blunt physical damage.

Moon Dregs can also serve as a protective barrier around Junpei's body. Yuuji's punches are partially absorbed when Junpei retreats inside the shikigami.

His combat experience is extremely limited, however. Junpei acquires his technique only shortly before using it against other people and never receives systematic sorcerer training.

Junpei first witnesses Mahito murdering people inside a cinema. Instead of immediately attacking him, Mahito recognizes Junpei's resentment and begins cultivating his curiosity.

Mahito teaches him about cursed energy and encourages his belief that human lives do not possess inherent value. Junpei gradually starts treating Mahito as someone who understands the cruelty he has experienced.

His outlook begins changing after meeting Yuuji. The two bond over films, and Yuuji later visits Junpei's home, where Nagi Yoshino immediately welcomes him.

Mahito secretly places one of Sukuna's fingers in the Yoshino home, attracting a curse that kills Nagi. He then manipulates Junpei into believing one of his school bullies is responsible.

Junpei attacks Satozakura High School with Moon Dregs and confronts Shouta Itou. Yuuji intervenes and gradually convinces Junpei that his assumptions may be wrong.

When Junpei finally turns away from Mahito's ideology, Mahito uses Idle Transfiguration to transform him. Junpei dies shortly afterward despite Yuuji desperately asking Sukuna to save him.

Nagi Yoshino is Junpei's mother and the person he loves most. Her relaxed parenting and unconditional acceptance give him a safe home despite the misery he experiences at school.

Yuuji Itadori becomes Junpei's first genuine new friend in a long time. Their shared love of movies creates an immediate connection.

Mahito presents himself as a mentor who understands Junpei but actually treats him as an experiment and a tool for psychologically damaging Yuuji.

Shouta Itou is one of Junpei's principal bullies and participates in physically abusing and humiliating him.

Sotomura is a teacher who recognizes that Junpei has been bullied but fails to intervene effectively while it is happening.

Moon Dregs is Junpei's shikigami and the supernatural ability through which he first begins actively fighting.