"[Jupiter] has the best grades, and coaches make her starter on whatever team has the most pressing need for someone who can do sports. She's a perfect role model, except for how she always misses the winning goal and blanks on the last question. She leads when no one else wants to, which is always."
Jupiter is one of the three main characters in We Know the Devil. She is described as a tomboy, and she has a very relaxed attitude towards most of the events of the game. She is a member of Group West, along with Venus and Neptune.
Jupiter typically has a "go with the flow" type of attitude, and doesn't concern herself much with other events. The only main exception to this is her fear of the Devil and of being a bad kid. She is constantly afraid of being "bad," and goes out of her way to try extremely hard to be seen as good.
Jupiter is anxious and shows a tendency to blame herself when things go wrong. An example is when she and Neptune go to the greenhouse and she breaks an old cabinet by accident, which causes her to start crying. Whenever she feels nervous or believes she has made a mistake, she snaps a hair-tie against her wrist.
Jupiter feels guilty frequently about being bad, but she also is afraid of intimacy and her feelings for other people. This is especially apparent in her feelings for other girls, and when she states in the Red ending that she is afraid of touching others. Jupiter also appears to be very uncomfortable about the fact that she is a lesbian, as she becomes very self conscious upon having to admit her feelings for Neptune, and gets uncomfortable when Neptune states that she doesn't seem like she would chase after a man.
Jupiter was raised by her mother and her father; her father is implied to be gay and is more relaxed in her upbringing. However, her mother was more strict, which led to Jupiter's stay in the summer scouts. Jupiter did well academically and was an athlete on some sports teams. Growing up, her mother dissuaded her from touching others because it was "rude," while her father told her to not let people touch her as it was dangerous since she was a girl. As a result, Jupiter has a strong craving for physical contact and seems reluctant to have intimate connections with others.
Prior to the events of We Know the Devil, she had been in the summer scouts for most of the summer, and was in Group West. She got along okay with the other groups in the summer scouts, however she was mocked and called the "#1 untouchable tomboy prude."
Jupiter trusts and confides in Venus because she thinks of her as "safe," and doesn't outwardly express romantic interest in her. Jupiter is willing to listen to Venus when she discusses the things that make her angry and her view on the world, although Jupiter doesn't always understand exactly what Venus means due to their very different world views.
Jupiter is aware of Venus's jealousy towards her, and it makes her rather uncomfortable, and directly calls out Venus on it and says it's "weird." However, like most other things that make her uncomfortable, she just lets it roll off her and bottles her emotions, until they explode resulting in her devil hands attacking Venus, which she immediately regrets and apologizes for.
Jupiter has a crush on Neptune, and while around her tries to play herself off as cool to impress Neptune. Whenever Jupiter fails to do so, or she does something she's worried upsets Neptune or makes Neptune's impression of her worsen, she snaps her hair tie against her wrist. Jupiter despises herself and feels guilty and ashamed for her feelings towards Neptune, and if she kisses Neptune during seven minutes in heaven she can't help but feel guilty and say that she hopes nobody ever finds out about what happened.
- The Zodiac sign related to Jupiter is a Sagittarius, so there's a possibility that she is a Sagittarius. The traits of a Sagittarius are often described as wanting to be free, to go on an adventure. In the context of the game, this relates to the touching motif.
- Jupiter is the shortest member of Group West.