Shunshin Hokai-o

Appearence
Shunshin Hokai-o has a relative similar appearance to, though this is just a cosmic coincidence, as they have no relation to each other. Shunshin, like all of his clan members, has shockingly red hair, and fair skin. His eyes are a reddish brown, which matches his hair a lot better than that of his brother, and wears no armor, instead opting to wear the more up-to-date attire for a Leaf Ninja. Despite having many visual dissimilarities from his older brother, Shunshin is more like him then their sister.

Personality
Like Entei, Shunshin also carries a serious persona to him. However, unlike him, he knows when to loosen up and joke around when the occasion presents itself. The main difference between Shunshin and Entei is that Shunshin does not have a love of historic things, and therefore does not dress, nor attributes himself to the proportions of the past. Instead, he tends to be more of a "current events" type of guy, dressing in Konoha attire of the 5th Hokages reign, despite being from the 3rds reign, and going out of his way to remain a "cool guy" (like that of a teenager) even though he is in his late twenties in current events. It is this opposite personality trait that often gets him in arguments, (albeit friendly) arguments with Entei.

There personalities are not completely different. They both have a deep sense of loyalty,protection of the village and clan, and both are very strong with there respective abilities.

Birth-to-Academy
Entei Hokai-o was born to Hishu and Benihime Hokai-o, in Konohagakure, during the 3rd Hokages original rule, as well as at the end of the Second Great Shinobi War. He was born second, meaning that he was simply the back-up plan should something happen to Entei (such as death) so that Shunshin would become the clan leader in his place, however while growing up, Entei always treated him as a complete equal. Shunshin was two years behind Entei. When Shunshin entered the Ninja Academy, his brother was already half-way through his time there. However, Shunshin often received help from Entei, who would assist him with his basics.

Shunshin graduated the Academy at the age of 12, becoming a Genin when Entei became an ANBU Operative.

Genin Career
Shunshin was ironically paired with his sister, Akasume Hokai-o, and childhood friend Suika Uzumaki, and their sensei was the same as his brother, Tenraku Uchiha, however it was later an unknown replacement to get them ready for the Chuunin Exams, given that Tenraku had been killed. Outside of completing the minimum amount of D-Rank missions, and one C-Rank mission, not much is really recorded of Shunshins time as a Genin, however the Nine-Tailed Fox did make its attack whilst he was one. Shunshin took the Chuunin Exams, but passed on his second try. He claims that his first failure was due to him "keeping with the cool".

Chuunin Career
Shunshin was known to be a very good Ninja Academy teacher, being very fair, and patient. He made a very good effort in connecting with his students personality and interests, (most likely keeping up with his "cool guy" thing). Outside of that, his missions during this time were mostly guarding things, low-level escorts, and once, a Chuunin Exam Proctor.

Tokubetsu Jonin
Shunshin was promoted to the rank of Tokubetu Jonin at the age of 17, just a year after his brother Entei.

Shunshin became a Tokubetsu Jonin due to his ability to track people, and find hidden traps, despite not having any abilities as far as being a Sensor, or having any Hiden Jutsu like Entei. To current events, he is still a Tokujo in the ANBU.

Ninjutsu
Shunshin takes great pride in his adept abilities using and  techniques, effectively able to use one after the other (a Katon, then a Raiton) in rapid succession. He claims it's to reflect his name, (Shunshin=Flash God).

Taijutsu
Shunshin has one area of expertise that outweighs his brothers, and that is Hand-to-Hand Combat. While Entei uses a Flame Release technique to augment his Taijutsu, Shunshin uses to up his physical abilities, which gives him greater speed, and a far deadlier "punch".

Trivia
Shunshin looks like. The author did this to put emphasis on the pride Shunshin carries, and how important he values love over power. Its also a connection that both characters have great skill in otherwise normal Elemental power.