Sludge Villain Incident

The Sludge Villain Incident is an event that takes place during the Entrance Exam Arc.

Prologue
At 12:02 PM (PM 0:02) in Musutafu, Japan, the Sludge Villain robs what appears to be a store and flees through the streets with his quirk active. The theft draws the attention of many bystanders including All Might himself.

All Might pursues the villain, but the Sludge Monster escapes into the cities sewer systems. Desperate, the Sludge Villain happens upon Izuku Midoriya in an alleyway and tries to apprehend his body in order to hide from All Might.

Incident
The Sludge Villain attacks Izuku and tries to invade his body. Izuku struggles but is unable to get free from the villains fluid body. Before it's too late for the young body, All Might arrives and saves him.

All Might stores the pieces of scattered sludge inside two empty soda bottles and wakes up Izuku. Izuku meets his childhood idol in All Might for the first time. Overly excited, Izuku hangs onto All Might's leg after the hero takes to the air. This loosens the bottles from All Might's pocket while they're in the air and the Sludge Villain gets free after falling to the ground.

The villain finds his next victim in Katsuki Bakugo, who is hanging out with his middle school peers. The Sludge Villain attacks Katsuki and tries to take over his body. He envelops Katsuki's body in sludge and takes control of his quirk. The explosions draw the attention of nearby Pro-Heroes, All Might and Izuku Midoriya.

The nearby Pro-Heroes are unable to help Katsuki because of the explosions. Kamui Woods saves nearby civilians and Backdraft attempts to put out all the fires ignited by the explosions. The Sludge Villain nearly kills Katsuki, but Izuku Midoriya inspires All Might to save the day.

Aftermath
After the Sludge Villain is apprehended by the police, Kamui Woods and Death Arms scold Izuku for rushing into the dangerous situation. Katsuki receives positive media attention for being the victim and is praised by Pro-Heroes for his quirk and his bravery. Katsuki eventually finds Izuku and reminds him that he did nothing to help the situation.

Afterward, All Might finds Izuku. Izuku's actions not only inspired All Might to act, but it leads to All Might choosing Izuku as his successor.

Fights

 * All Might vs. Sludge Villain
 * All Might vs. Sludge Villain: Rematch