The Brain and Brawn Brothers

The Brain and Brawn Brothers (天才と筋肉兄弟, Tensai to Kinniku Kyōdai) was a self-proclaimed team of the genius older brother, Fukegao, and the muscular younger brother, Marugori. When Fukegao invented the steroid, Biceps Brachii King, his brother ingested it and transformed into a mutated giant. Together, they allegedly combined the highest intelligence and highest physical power and strove to control the world. The brothers destroyed D-City, and soon after, Saitama was found on Marugori's shoulder. Fukegao told Marugori to kill him and he accidentally killed Fukegao. Saitama then defeated Marugori, wrecking B-City in the process.