Birds wears a green Kokuyo uniform, and top hat. He is an old man, but broke out of prison to aid Mukuro in finding Tsuna. He has multiple yellow birds which follow him around and double as a signal to Mukuro if he is defeated. Birds also seem to find pleasure in other peoples pain, as he has a nosebleed when ordering Tsuna's friends to beat him.

Nowadays, the mafia world is ruled by Italy's strongest family, the Vongola. Vongola's current head, ninth in the row, is an old man ready for retirement. But before he can hand down his position, he needs help from a professional Hitman to prepare the next generation Boss for ruling over Vongola and the mafia world itself. 
Sawada Tsunayoshi is just your ordinary teenage boy who attends Junior High and sucks at it. He is unpopular, has no friends, and is desperately in love with a girl from his class. But his life takes an extraordinary turn when Tsunayoshi meets Reborn, an infamous hitman, who the ninth boss of Vongola has sent to train Tsunayoshi for his upcoming title. 
(Source: Katekyo Hitman Reborn! FC)

Sawada Tsunayoshi is regular boy who has never excelled in sports, school or social life, thus being named "No Good Tsuna". Everyday, he leads just a normal life, living with his mother, while his father is away for work. But the thing Tsunayoshi doesn't know is that his family is actual lineage of the great Mafia Boss, the first head of Vongola, Giotto. 
Because of the Sawada history, Tsuna has been chosen to become tenth head of the Vongola family, an infamous Italian mafia family which rules the Mafia world. To become worthy of the title, Tsuna is being aided by professional hitman and infant, Reborn, who takes the role of Tsunayoshi's mafia tutor. 
(Source: Katekyo Hitman Reborn! FC)
 
Note: Chapter count includes two extra collections of short chapters published in volume 42