Simon Decimo & Guardians are the main 10th generation members of the formerly powerful Simon Famiglia. All members of the current Simon Famiglia are childhood friends with Enma and were subsequently chosen to be in his Family. The seven guardians of the family all possess one of the rare Seven Flames of the Earth, its powers being said to be able to rival the Seven Flames of the Sky.
The tenth generation boss of the Simon Famiglia, Enma is a gloomy and introverted transfer student at Namimori Middle School. He previously attended Simon Middle School with the other members of his Famiglia before an earthquake hit their area. Not much information is revealed about his past except for the fact that due to Vongola Primo's "betrayal" of Simon Cozzato, the Simon Famiglia shrunk in power; because of this, Enma's family suffered persecution since he was young, and he grew up resentful towards the Vongola Famiglia, his resentment was fueled further when Demon Spade, disguised as Iemitsu Sawada, murdered his mother, father, and sister. Enma possesses the Earth Flame of the Seven Flames of the Earth.
A member of the tenth generation Simon Famiglia, Adelheid is a strict and reliable member of the Famiglia and is often the one to take care of the other family members. She too, previously attended Simon Middle School with her Family before the earthquake and was subsequently transferred to Namimori Middle School. She is fiercely loyal to the Famiglia cause and expects the other Simon members to show the same amount of loyalty no less. Not much is known of her past except for the fact that she had attempted to carry the burden of the Simon Famiglia and broke down as a result; it is also implied that she was romantically involved with Julie Kato before Demon Spade possessed his body to use as a vessel. Adelheid possesses the Glacier Flame of the Seven Flames of the Earth.
A member of the tenth generation Simon Famiglia, Julie is shown to be a carefree and relaxed individual, often ignoring his Family duties, resulting in frequent clashes with Adelheid. Previously attending Simon Middle School, he and the rest of the Simon Famiglia transfer to Namimori Middle School after an earthquake hit their area. He is the most detached member of the current Simon Famiglia and is not on good terms with the rest of its members; however, it is later shown that Julie was being possessed by Demon Spade for an untold period of time, and that the real Julie Kato was unconscious. Not much is known about his past except for the fact that he may have been romantically involved with Adelheid Suzuki at some point as seen from a flashback. Julie possesses the Desert Flame of the Seven Flames of the Earth.
A tall and muscular member of the tenth generation Simon Famiglia, Kaoru, along with the rest of his family, transferred from Simon Middle School to Namimori Middle School after the earthquake. Kaoru is noticeably the oldest of the Simon Guardians and does not resemble a middle schooler. Despite his fearsome appearance, he is shy and timid at heart, though he seems to easily resort to violence when he feels threatened (he is known as "The Hospitalizing Devil Kaoru" by Koyo). Kaoru possesses an Unknown Flame which is part of the Seven Flames of the Earth.
A member of the tenth generation Simon Famiglia, Koyo, like Ryohei, has a love for boxing and refers to himself as "The Hope of the Boxing World". He transferred to Namimori Middle School along with the rest of the Simon Famiglia members after the earthquake. Koyo is extremely brash but loyal to his Family, becoming enraged when others talk negatively about it. Despite this, Koyo seems to be on bad terms with the other Family members as he frequently makes fun of Enma and calls Julie "lazy"; he seems to have more respect towards women, however. Like Enma, he has an extraordinary amount of hatred and resentment towards the Vongola. Koyo possesses the Forest Flame of the Seven Flames of the Earth.
A member of the tenth generation Simon Famiglia, Large is a large but quiet guardian for his Family who also transferred from Simon Middle School to Namimori Middle School due to an earthquake. He does not seem to have problems with taking orders from others and was shown to be an extremely kind and considerate member of the Family, often protecting Enma from bullies on their way home from school, later, it is shown that Large is also quite cruel and fiercely loyal to Enma, whom he has great respect for. He too, has a hatred towards the Vongola Famiglia, but acknowledges Lambo as a friend. Large possesses the Mountain Flame of the Seven Flames of the Earth.
A member of the tenth generation Simon Famiglia, Shitt P! is very intelligent and confident, she has the most eccentric look of all the members of her Family. Shitt P! and her Family transferred from Simon Middle School to Namimori Middle School after an earthquake hit their area. Her pride contradicts that of Gokudera's, who fights for his Family and Tsuna, while P. loves herself and fights on behalf of herself. Despite this, she mentions later in the manga that she "wishes she had met Gokudera sooner" and expresses an interest in him. Shitt P! possesses the Swamp Flame of the Seven Flames of the Earth.