Proper Japanese Title: 銀魂 (Gintama)
Originally serialized in Weekly Shonen Jump. Translated (partially) into English as Gin Tama by Viz.
Gintama is a comedic action manga that can make drastic tonal shifts throughout the series from dark and serious to completely bizarre gags or one-off chapters that have no real effect on the progression of the story and may not even feature any of the characters from the series (such as a chapter where characters that resemble the main cast are seen talking without showing their faces for the entire chapter before the end reveals it was just a bunch of one-off characters that resembled the main cast apart from their faces and none of the stuff they said throughout the chapter had anything to do with the characters they resembled). However, generally, it combines the two tones and is generally regarded as a gag manga.
Though it has not been able to sucessfully translate well to the West due to its content (from the style of humor to numerous obscure or cultural references), in Japan it has been successful both in its original manga form and anime and film adaptations.
Though the series is set in the future when aliens have colonized Earth, many of the character's names are inspired by figures from Japan's history (specifically the period of the Meiji Restoration), due in part to the original plan for the Shinsengumi to be the focus of the manga. Below is a list of real-life inspirations for character names (being important and popular figures in Japanese history, the real-life inspirations for the Gintama originals have often appeared in other manga):