Ikkyuu

The dying wish of Ikkyuu's grandpa was for him to take good care of the temple. But with the temple being used as the collateral to a massive debt and Ikkyuu still only in high school, it seems inevitable that the land would be sold off. Ikkyuu realizes how important the temple is to the community and remembers the promise he made to his grandpa and takes a long shot: going to a loan company through a recommendation. There, a man named Kawachi agrees to pay off the large debt under one condition: Ikkyuu must participate in an underground fight club called the Clash Club where people watch and gamble online on a street fight with absolutely no rules. Ikkyuu must keep winning to save the temple and save his life that hangs by a thread with every fight.

(Source: MangaHelpers)