Legendary Leader Shou (Densetsu no Kashira Shou)
Previous group: MangaCity
http://www.mangatraders.com/manga/series/627

Summary (edit):
This total loser, Tatsuhito, causes the legendary gang leader of the Grand Cross, Shou, to be hospitalized. He must take his place for the duration of time it takes for Shou to recover or else the Grand Cross would fall into chaos.

Only Volume 1 has been scanlated, so I guess you could read and see if you like it.
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I might have some of the raws for this, will have to look on my old HDDs.