The Tomaso Famiglia is a Mafia family that is supposedly a rival of the Vongola Famiglia, having said to have skirmishes in the second generation, being enemies with Longchamp II. However, their current leader-in-training, Longchamp Naito, seems more focused in making friends with Tsunayoshi Sawada than actually starting a war with him, unaware of their rivalry (that, or he simply doesn't care). Also, just like Longchamp, his family is pretty eccentric in their own right, such as Longchamp's subordinates having frequent internal disputes.
It is suggested in the future that the Tomaso Famiglia remained close with Tsuna through the years, but nine years and ten months later, they are targeted by the Millefiore Famiglia. Two days prior to Tsuna's arrival in the future, Vongola has already lost all contact with them and they have since been reported missing.
They were many other members shown in an internal skirmish when Lambo had been sent flying into Naito's courtyard by Reborn. It is hinted that internal conflict happens frequently in the Tomaso Famiglia.
- Desolation Bullet - causes a person to grieve about all the terrible things that have happened in their life, making others feel sorry for them.
- All of the members are named after cars from De Tomaso, an Italian car-manufacturing company.
- The Tomaso Famiglia has so far been a manga only Famiglia, making no appearance in the anime version of the series due to its unpopularity.
- All Tomaso Famiglia Bosses' first names are Longchamp.