This is one of the best manga series I've ever come across! Hell, what do you get when you mix in a bunch of babies with guns, poisonous food, dynamites and characters that don't make sense at all? You get CRACK, or Katekyo Hitman Reborn.
Tsuna is your average loser-geek. He gets picked on by his schoolmates, is always chosen last in sports and is useless in every way. Enters his home tutor, Reborn. In fact, Reborn isn't just a home tutor. He looks like a baby, wears Mafia-like suits and owns a pet chameleon that sits on his hat. He tells Tsuna that he came to Japan to train Tsuna to become the 10th Boss of the Vongola (Mafia) Family!
So begins Tsuna's wacky adventure as he deals with Reborn's strange training. Along the way, Tsuna and Reborn recruits new members into the Vongola family (as in guards to protect the 10th Boss)-- Gokudera Hayato, the exchange student from Italy that is also known as 'Smoking Bomb Hayato', and Yamamoto Takeshi, Tsuna's baseball-playing friend who assumes that everything that is just a 'Mafia-role playing game'.
Then you get Reborn's lover, Beyonce, who masters in Poisonous Cooking; Hibari (gangster-ish head prefect), Yuuta (a boy who can accurately predict rankings), Dino (was previously trained by Reborn and owns a pet turtle), Rambo (a cry-baby baby assasin from the Bovino family out to kill Reborn) and Kyoko, the girl that Tsuna has a crush on.
Although it is a series, each chapter can be read almost separately, which makes it easy to read. The story is light and funny, but recent developments in the manga is leaning towards a more serious story arc. If you haven't read this series, I recommend you check it out! Guys will love the fighting scenes and the humour, and the girls will er... love the handsome guys. ^^