Ueda Yumeto

Hideo Kawamura has a really terrifying look, but soft heart. While contemplating suicide, he stumbled upon this computer that contained the virus, "Wiruko", who convinced him to join the "Seimahei", a fighting tournament that has the world as its prize. However, Hideo happens to not have any fighting skills whatsoever, so he has to get through on his wits (and luck) alone.