A few days before the Brawl
Detective Tsukauchi and Kai rode in a patrol car to Tartarus. They needed to interrogate Chisaki on where the Shie Hassiaki were hiding and stop the distribution of the Trigger.
The guards practically had to drag Chisaki to the room. He refused at first to talk to the Detective and his so-called "hero" counterpart.
"What do you want?" Chisaki sighed.
"We need your help in order help in order to find the Shie Hassiaki." Tsukauchi said.
Chisaki scoffed and crossed his arms.
"What is in it for me?" Chisaki said.
He gasped when he saw Kai take off his mask. He looked like the spitting image of him.
"Who are you?" Chisaki hissed.
"I'm you." Kai said. "From another world."
"Likely story." Chisaki doubted.
Kai shook his head and said, "Think about it. No two quirks are the same. You saw me use my quirk in the fight. They were identical."
Chisaki rolled his eyes.
"Like I said, what's in it for me?" Chisaki inquired.
"We can cut you a plea " Tsukauchi suggested.
Chisaki waved his hand in order to gesture disagreement.
"As if a prosecutor will reduce my life sentence." Chisaki said.
"Kai, I know there is one person in the world you care about." Kai said.
Chisaki raised his eyebrow.
"Ooh? Do tell?" Chisaki said.
"Pops." Kai said.
Chisaki was taken back. He was caught of guard. Kai was right.
"If you care for Pops as much as I do, then I know you are in agony now you can't reverse his coma." Kai said.
"I can reverse his coma." Kai insisted.
Light returned to Chisaki's eyes. For once, he was hopeful.
"How would I know you will keep your promise? Chisaki questioned.
"It's a hero promise." Kai said.
Tsukauchi later explained they will put it in a contract.
Chisaki quickly told the Detective and the Pro Hero the current location of the Shie Hassikai and where they were producing the drug Trigger.
Sir Nighteye pulled together his raid team and caught the Yakuza red-handed.
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"Do you know what you are doing?" Chisaki questioned.
"Hey, I have medical knowledge like you do. I actually went to med school." Kai insisted.
Kai gently placed his hands on their old man and activated Overhaul.
Chisaki was impressed. It was quite clear Kai was more skilled than him.
Moments later, Pops woke up and was surprised to see two Kais. Especially since one of them was an amputee.
Chisaki got down on his knee and apologized. He shed a tear.
The Boss was taken back. He never expected to see Chisaki apologize in his entire life and actually mean it.
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.
.
"There is one more thing you guys have to worry about." Chisaki said.
Kai was all-ears.
"We were working on a Quirk-Erasing Bullet." Chisaki explained.
"What the fuck?" Kai said.
"Don't curse. Our Old Man wouldn't tolerate that." Chisaki said.
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.
.
Despite Chisaki's warning, a couple of heroes lost their fights. Even Lemillion.
Though it was worth it if it meant taking the Shie Hassaikai once and for all.
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.
.
"Can I see Eri?" Kai asked.
"Bad idea." Aizawa snapped.
Kai was expecting this response but he was still surprised his idea was shot down. He miss his world's Eri.
"If I can't see her, can I leave a written idea on how Eri can safely used her quirk?" Kai suggested.
Aizawa nodded in order to show he obliged.
With the help of Izuku's analysis, they were able to speed the process of Eri learning to use her quirk. Soon, they should be able to reverse the heroes' quirklessness.