Gokudera was born in Italy and is 3/4 Italian and 1/4 (mother) Japanese. 
His blood type is B, is 168 cm tall, weighs 54kg and his hair is silver. His future dream 
is to become the Tsuna's right-hand man. He has an ability to play the piano. He dislikes 
people that are older than him, Bianchi and Lambo. Gokudera is also a chain smoker, but 
they remove this in the anime adaptation.

At school, Hayato is adored by many of the female classmates who view him as the 
"rebellious badboy." During Valentine's Day, a large group of females constantly followed 
him around trying to give him chocolate, although Hayato seemed to be more annoyed
 than flattered by this. Despite his image of a rebel, Hayato excels in his schoolwork and 
aces all his tests, much to the surprise of Tsuna. This is probably due to his rich 
upbringing, suggesting that he probably had a multitude of private tutors when he was 
young. He idolizes Tsuna greatly and considers himself to be Tsuna's right-hand man.

Due to a traumatic childhood experience, every time he sees the face of his older sister, 
Bianchi, he becomes sick, sometimes even falling unconscious. Oddly enough, he is 
immune to his sister when she happens to be wearing something that covers part of her 
face (i.e. glasses or goggles).

When he was younger, he was a talented pianist. However, he soon grew tired of 
playing after his 'trauma', and instead, decided to join the Mafia. Unfortunately, since 
he was considered to be a mere pianist, no one wanted to accept him into their family; 
the fact that he was an oriental half-breed lessened his chances of finding a willing 
Mafia family to take him in. To become stronger, he sought advice from Dr. Shamal, 
who, at the time, was working for his family. Hayato seemed to have looked up to 
Shamal, to the point that Shamal believed Hayato to have copied his hairstyle, and 
even wanted to learn his assassination technique, the Trident Mosquito. Instead, 
Shamal taught him how to use dynamites, which caused Hayato's fascination with 
explosives, eventually choosing them as his main weapons.

In the future arc, more was revealed of Gokudera's past. He and Bianchi are actually 
half siblings, born by different mothers. Bianchi's mother was married to their father 
but Gokudera's was a woman with whom he had an affair. Gokudera's mother was a 
young, beautiful woman and a very talented pianist, whom their father fell in love 
with at first sight. Not long after, they became involved and the woman bore a child. 
However, in the mafia, illegitimate children are not tolerated, and everyone was told 
that Gokudera Hayato was actually from the same mother as Bianchi.

His real mother was allowed to see him three times a year until he was three, when 
she was killed after driving off a cliff on her way to see her son. It was probably not 
an accident, because, as Reborn says, "It slid off the road at an impossible location. 
It's been said that there weren't even tire marks. It was instant death." Suicide was 
considered, but she had been looking forward to that day and had even brought a 
present for the young Gokudera. Gokudera himself was unaware of what had happened 
until he was eight. He had overheard some servants gossiping and fled the mansion 
the day following.

Kotaro Katsura (桂小太郎)
Birthday: June 26
Zodiac: Cancer
Height: 175 cm
Weight: 56 kg
Age: 20's

Katsura is Gintoki's former comrade during the Joi war. Even after the Amanto take-over of Japan, Katsura continues to resist the Amanto, and has amassed a band of followers. His weapon of choice is a metallic grenade. He is a wanted man due to his involvement in terrorist activities against the Bakufu, and is constantly on the run from the Shinsengumi. Although his initial methods were originally more violent in nature (for instance, sending a bomb to an Amanto embassy), Katsura has gradually grown to believe that there are people important to him in Edo, and decides that he no longer wants to destroy the country, but believes there should be a way to change it without causing sacrifices.

Katsura seems to be highly respected by his followers, and has even been called the "Daybreak of the Joui Faction" by some. When people believed that Katsura had died during the Benizakura arc, even other terrorist groups tried to avenge his death.
Since he is a wanted man, Katsura is often seen wearing disguises, although his identity is often still easily found out. One example of a disguise he seems to be fond of is a pirate's costume, complete with an eyepatch (with a skull design) over his left eye and a scar on his right cheek, and using this he calls himself 'Space Captain Katsura'.

Katsura seems to possess a rather outdated sense of humour, and sometimes refers to things from a past era, such as when he tried to buy a Famicon when people were queuing up to buy the OwEe (a parody of the Wii). He also seems to have a tendency to make up dramatic stories, which moves others to tears when they hear these stories (except Gintoki).
Katsura sometimes works odd jobs (e.g. in Episode 88), to raise money for his terrorist activities. He claims that his heart has started to be moved by Ikumatsu in episode 39 (chapter 55 equivalent of the manga), and held his subsequent interview in her ramen restaurant.

In the Japanese version, Gintoki often calls him "Zura." In the first English volume, Gintoki calls him "Casserole," or "Cough syrup." Eventually, the English version changed to Gintoki calling Katsura "Zura." In the Japanese version, Katsura indignantly replies "Not 'Zura'! It's Katsura!" (and will do so anytime he is called something other than his name). In the English version he replies "Not Casserole! It's Katsura!" The Japanese version joke is a pun, since "Katsura" can mean wig in Japanese and "Zura" is slang for the same thing. The English version is also a wordplay since "Katsura" and "Casserole" sound somewhat similar in pronunciation. He has the uncanny ability to know when someone has called him something other than Katsura, even in their head. An example being in Episode 25 as a guest to Gintoki's hotpot dinner.

Katsura's birthday is June 26, making him a few months older than Gintoki, and in his twenties. His height is 175 centimeters, and he weighs 56 kilograms.
His name is based on the historical Katsura Kogoro.

Hijikata is the famed chain smoking, vice commander of the Shinsengumi so named by his 
subordinates, because of his fearsome demeanor. Purportedly the brains behind the force, he takes his work 
seriously, and is fiercely loyal to his leader, Isao Kondo.

Hijikata has a reputation as a fearsome leader, earning the nickname of "demonic vice-commander". 
He is also hot-tempered and often speaks of seppuku. However, despite his cold exterior, he does 
have a more compassionate side. He also has a tendency to cry after watching movies that are not 
particularly emotional.

Hijikata is obsessed with mayonnaise and thus has the nickname "Mayora". He has been known to smother 
anything he eats under a mountain of mayonnaise, and he carries a number of objects shaped like jars of 
mayonnaise, such as his cigarette lighter. He was popular with girls until they discovered this obsession.

He enjoys fighting and sees Gintoki as a rival in practically everything he does from drinking contests to 
rock, paper, scissors ever since being defeated by him in battle. He is in constant danger of being killed 
by the attempts on his life by Okita. But, despite all this, he sees Okita as one of his close friends, and 
vice versa.

Before joining Shinsengumi, he used to be a trouble-maker ronin. He enjoys fighting/having a good fight and 
says he doesn't care how many Amanto buildings get blown up, he only looks forward to having a big battle 
with the Joui rebels after Shinsengumi has rounded them in 1 fell swoop, in Episode 5.

He also formulated the Kyokuchuu Hatto, the 45 Regulations that form the disciplinary framework for 
Shinsengumi members, and implements them firmly.