[kiak666]

Chapter 20 is translated in Chinese, and looks like this is the beginning of our first major story arc.

Spoiler for Chapter 20:

All Might has indeed overexerted himself to beat the brain monster, a fact that only Izuku notices. He's using the last of his strength to act tough in order to scare away the remaining two villains.

However, the plan doesn't work out, as black mist guy manages to convince Shigaraki to attack All Might together. When the attack almost connect, Izuku manages to jump in to grab the mist guy using One For All, an act which fractures his legs. Angered that their attacks were intercepted, Shigaraki attempts to kill Izuku, but was stopped by the timely arrival of the other teachers of Yuuei, whom are brought over by Iida.

Realizing that they're seriously outnumbered, Shigaraki escapes using the portal created by the mist guy, but not before promising that he'll kill All Might the next time they meet. As the battle draws to a close, Izuku expresses his frustration, as he was unable to do anything to help. However, All Might (in his skinny form) assures his protege that he would be dead if it wasn't for Izuku's timely intervention.