Inko knows!

"So, you're going back to the Heroics classes tomorrow?" Inko asked as she collected the dishes, but was stopped by Izuku.

"Let me, and yes," Izuku told her, taking the dishes, and heading for the sink.

"That's good. Are you going to bring back another girlfriend with that genie of yours?" Inko then asked him, sitting down.

"Probably Hatsume next, we..." Izuku started to absently answer, before freezing. It was a good thing he had already put the dishes in the sink, otherwise he would have dropped them. He slowly turned towards his mother, the harem also staring at her as she casually took a drink from her tea. "...okay, when and how?" Izuku sighed, face palming, already kicking himself for whatever mistake he'd made that allowed his mother to find out about it.

"Right after the USJ attack, when Momo and Ochaco came to talk to you about it," Inko replied. "I had come upstairs to check on you, and overheard you talking about the matter."

"Wait, didn't you wish for the room to be sound proofed Izuku?" Ochaco asked, looking towards Izuku, who nodded.

"One of you left the door partly opened, pushed mostly closed, but there was a crack. I was wondering why I never heard a thing when you lot were clearly having your fun up there, but that answers that question," Inko noted, and Ochaco flushed, realizing it was her. "I quietly shut it when you got started that time. I later found the lamp in your room, confirming the whole genie thing, but left it be."

Izuku slammed his head against the sink, trying to remember exactly what they had talked about that time. If he recalled correctly, he had talked about his worries that power would corrupt him, and Momo reminding him about what his second wish had been. "...and you didn't say anything?"

"You were being responsible enough with it, and you were happy, so I decided against bringing it up," Inko shrugged. "Though I do have one question."

"What's that?" Izuku asked, straightening, and making a mental note to make a wish to ensure he was never overheard again. This little running gag has gone on long enough.

"What's One for All?" Inko inquired, and Izuku groaned and face palmed. DEFINITELY needed to make a wish to avoid being overheard again!