Oomori! Nariagari Meshi

Oomori High School is a one-of-a-kind high school for delinquents. Leo, a first-year student, spends his days fighting in his quest to reach the top, but Kenny, the leader of the second-year class, stands in his way. Kenny's weapon isn't his fists, but his "bento" lunchbox...?! A gourmet comedy about the strongest delinquent who rises through the ranks of the delinquent school through the power of food!

(Source: Shinchosha, translated)