The first fight when the S class raids the MA base was Flashy Flash vs Gale & Hellfire which was Chapter 60 of the webcomic. Chapter 70 we have Tatsu vs Psychos on the surface(yes all the other battles happened like Zombie vs Pureblood, Amai Mask vs Fuhrer Ugly etc). Just 11 chapters. In the manga, Flashy Flash vs the Ninjas was chapter 94 so 41 chapters so far.