Tokyo PD, Main Headquarters.
"So, do we have any intel on who the person is?" The police commissioner of Tokyo city asked Kataoka.
"No sir, but the computer is going through all the criminal records of the country, if this guy is a known offender, we will find him." The detective replied.
Just then, a constable barged into the room, holding a few sheets of paper.
"Sir, we know who our suspect is..."
Immediately, the detective took the sheets and began reading the contents out loud.
"Okawa Kinji... Quirk: 'Forget me not'... When he activates his quirk, everyone who knew him for a period of 7 to 8 days will forget everything about him.
Known offences: Auto theft, armed robbery and multiple rape attempts, although he had never been successful in doing that. Although, it says that his quirk does not affect computers and cameras... That's how he was captured before... 20 years ago. After his sentence of 16 years was over, he disappeared completely." A picture showing the face of the man was also present. He had orange eyes with brown hair, and looked to be in his early 20s.
"Good job, all we need to do is find him somehow... But how? With a quirk like that, it'll be almost impossible to find him." The commissioner commented.
"That... is a problem." Kataoka said. Then, something in his mind clicked.
"Sir, I've got an idea. How about we send some of our undercover cops and put an advert about robbing a bank in the underground. That could lure him out. We can say that we need help with a bank job, and offer him a hefty reward if he joins." He explained.
"Yes... That can work. Good thinking!" He immediately took out the top secret registry and contacted all of the undercover cops.
That night, a top secret meeting took place in the headquarters. The meeting was so secret, that the commissioner asked everyone to uses pen and paper to converse, so that any sort of voice recorders will be useless. The only thing the commissioner said out loud was 'All Might will help us with the Investigation'. A few hours after the meeting, the search for the prime suspect began. All the undercover cops began setting up fake heist teams, to lure Okawa. For days, they searched, but weren't able to get any information on him, and the public were getting riled up due to the supposed clumsiness of the police, and the media were having a field day(s). They were spewing out stories about the possibility of corruption within the police ranks, etc. The police on the other hand were slowly beginning to lose hope. Day by day, many villains, new and old would approach the undercover cops for the heist. They were even contacted by a new villain hacker named Darklight, which they declined as they didn't need a hacker.
Few weaks later, things were still grim for the cops. They were five hours from aborting the mission when the person they had been looking for walked into on of the 'Villian' Hideouts.
"So... I hear that you people are looking for a sixth man for your heist?" He asked the 'villains'.
"You heard correct..." One of the officers replied.
"Well, I would like to join." He said calmly.
"Really? What's your quirk?" One of the villains asked.
"I can make people forget my name and how I look." Okawa answered.
"Wait here, we'll have to discuss this." The leader of the group said. After which all of them, leaving out the actual criminal, left. They went to a side room and confirmed that the man(Although older now) was definitely the one they had been looking for. After which they made a quick plan on how to arrest him. Five minutes later they came back to the main room.
"Alright... we'll hire you" The leader replied.
"Tomorrow, meet us outside the central mall jewelry shop. Oh, and if you even think of ratting us out..."
"Trust me I won't" As the conversation was going on, one of the cops got behind him knocked him out with a karate chop to the back of the neck. After which the leader contacted the commissioner.
"Sir, we've got him."
"That's the best news I've heard in a long time. Ok, bring him to the headquarters. And be careful to not blow your cover."
"Roger that" The leader affirmed and hung up.
"Alright people, let's get this S.O.B. to the head quarters. [3,ready the car. (BTW, all the numbers within [ ] are code names for the different members of the undercover team) [5, erase any and all evidence of us being here.  You're on sentry duty. [2, help me carry this guy to car.
1 Hour Later, Police Head quarters.
Okawa woke up to a bucket full of cold water. He opened his eyes to find himself in an interrogation room, with All Might, along with a detective, standing in front of him with a not-so-happy face. He realised that he was caught, but made a strong resolve to not open his mouth, no matter what.
"Now... I will ask you only once. Who is the person responsible for the massacre." All Might asked in a very dark tone.
"It was me... I did it." Okawa replied
"Because the law took away 16 years of my life!"
At first the answer was believable, but then All Might thought, why would he want to kill so many civilians. If he wanted revenge, he could've bombed a police station or let those maniacs into one. His suspicion turned out to be true when the detective gave his input.
"He's lying..." Kataoka said.
"I have a lie detection quirk. The truth is something else, and he's hiding it."
Then, unexpectedly, the criminal began to laugh.
"Hahaha, Yes... I am lying. You can beat me and torture me all you want... But there is no force on earth that can make me reveal who the person was. NOT EVEN YOU, ALL MIGHT" He yelled.
"Why you--" All Might was about to punch the guy into oblivion when he realised that he was the only lead on where to find the real mastermind.
"Dammit" He cursed under his breath. He knew he had to find a way to make him talk, or else many more lives could get lost. The tapped on the detective's shoulder and told him he had a few things to discuss. As the two of them were leaving the interrogation room, Okawa said something that put everyone on edge.
"Discuss all you want... Its only a matter of time before your society crumbles into nothingness." He said with a smirk.
In the briefing room, all the officers were trying to find a way to make Okawa talk. From torturing him to bribing him. Torture and bribe may work on some criminals, but Okawa seemed to have made up his mind. The discussions went on for three hours when one police man gave a possibly good solution. The officer went to commissioner, who was talking with All Might and Kataoka and gave his solution.
"Commissioner, sir. I think I know how we can make him talk." He said.
"My nephew has a brainwashing quirk. We can brainwash him into telling everything."