Jade Green, known in Japan as Midori Seto, is a character who serves as one of the three new managers for the Raimon soccer club. She is a middle school student in her eighth grade year, with a physical appearance marked by her long orange or red hair, often styled with distinctive blue ribbons or a hairbow, and her green eyes. Her typical attire consists of a white blouse paired with a long blue pleated skirt, a design that sets her apart from the other managers who wear miniskirts.

Her personality is defined by a strong sense of justice and a rough, no-nonsense attitude that belies a softer interior. She is known for being strict and for speaking her mind without hesitation, a trait that creates an initial impression of her as someone not easily provoked but also dangerous to cross. This tough exterior is balanced by a gentle side, and she is a tremendous supporter of the team's captain, Arion Sherwind, for whom she harbors a deep admiration. She once introduced herself as a member of his private cheering squad, demonstrating her dedicated, if somewhat intense, fandom. This combination of sternness and hidden warmth places her in the archetype of a tsundere character, similar in spirit to a previous Raimon manager, Nelly Raimon.

Jade’s role in the story is primarily as a manager for the Raimon team, yet she is far from a passive background figure. She is deeply invested in the team's morale and success. When members of the club began losing hope under the oppressive system of Fifth Sector, she became visibly distressed and even shouted at the players to reignite their fighting spirit. Her passionate speeches have been known to directly inspire the team to rebel against imposed orders and play to their fullest potential. She also provides practical support, such as tending to injured players, and serves as a source of emotional encouragement, particularly for Arion.

Key relationships significantly define her interactions. Her most prominent dynamic is with her teammate Ryoma Nishiki. The two are frequently seen arguing and bickering, yet it is implied that she genuinely appreciates him despite their constant conflicts. Jade reveals that she and Ryoma attended the same school during their first year, providing a backstory for their familiar, quarrelsome relationship. Her relationship with the other managers, Skie Blue and Rosie Red, is one of camaraderie, though she is not immune to being teased by them, particularly regarding her obvious crush on Arion.

Throughout the series, Jade exhibits notable development, particularly in the Chrono Stone arc where her personal interests are highlighted. It is revealed that she is an avid fan of historical films, specifically a fanatic of the Shinsengumi captain Soji Okita. This passion becomes a driving force for her character, leading her to enthusiastically participate in the time-traveling adventures. Her deep desire to meet her historical hero even causes her to argue with Ryoma about which historical figure to find first, showcasing that her motivations extend beyond simply being a soccer manager into a personal, enthusiastic pursuit of her own hobbies.

In terms of abilities, while her primary function is that of a manager, she is also classified as a forward in the games associated with the series. Her element is fire, and she possesses access to shooting techniques such as Shoot Pocket and Delta Attack, the latter of which she shares with Arion Sherwind. Her abilities, however, are not limited to the field. She demonstrates considerable physical strength and a forceful personality, with in-game profiles noting that she is a rough-and-ready girl who hates injustice. It is even said that she has a presence intimidating enough to scare off all the delinquents at the school.