He is a teenager who joins Gintoki's freelancer business to learn the ways of the samurai.

He stays at his family's dojo along with his older sister Tae Shimura, where both used to live there with their father who died when they were still children. In order to make their living, Shinpachi started working in a restaurant in which he met Gintoki.

Although he commonly criticizes Gintoki's lazy behaviour, Shinpachi comes to regard him as a very important person to him in the same fashion as Kagura.

Despite his meek appearance, Shinpachi is a more than competent swordsman of his family's Kakidō-Ryu, the school of swordsmanship his dojo teaches. Shinpachi is also the captain of the "*Otsu's Imperial Guard," an Otsu's fan club, and takes his role seriously.

*Otsu is Terakado Tsu(寺門 通) , a famous idol pop singer from Edo. She is often referred to as "Otsu" due to her habit of making words using the last letter of previous words (Terakad-O-Tsu).

He also appears in a crossover episode, alongside Kagura and Gintoki, for Sket Dance in episode 26.

Source:Wikipedia