Try it with Momo

Momo Yaoyorozu will stop by Mina Ashido's room, open her top to reveal her breasts, and produce milk for Mina to drink. She will not find this odd in any way.

Mina looked at the clock, after a few seconds, she resumed getting dressed. But she'd only gotten to new panties before there was a knock on the door. "Mina? Its Momo." Stunned by this, the acid user jumped over to the door and opened it, letting the class rep in. She was fully dressed in her school uniform.

"Morning, Momo. Why did you stop by?" She says, still a bit disbelieving as her friend walks into her room.

"Oh, I just wanted to give you this." The innocent rich girl then unbuttoned her uniform deeply, enough to show her valley of cleavage. Mina was getting a deep eyeful, but Momo didn't seem to mind. It looked like the book was real! which means she's going to reach down and... use her quirk to manifest a milk carton from her left breast... "This is for you. Milk's a good way to start the day, I even left out anything that would be bad for you."

Mina stares at the innocent face of her friend, a bit disbelieving. "Th-thanks." She takes the carton, and opens it to drink.

"Is something wrong?" The Creation Quirk user tilted her head at her friend, concerned.

"No! no, just... remembering an anti-climax from one of the movies I saw the other day." Mna said as she started drinking. She had been totally expecting Momo to breastfeed her... Maybe she worded it wrong?

"Well, I'll leave you to get dressed. It's a good idea to get to class early!" The big chested heroine in training rebuttoned her shirt before heading back out the door. Once Mina had finished downing the small carton, she let out a content gasp. It had been good milk, but she'd been hoping for more. She went over to the reality notebook looking it over.

"Momo Yaoyorozu will ... yadda yadda... reveal her breasts, and... produce milk for Mina to drink. Oh duh..." She felt dumb in hindsight for overlooking that detail. It would make sense for any other girl to breastfeed her with this, but Momo's Creation quirk meant that could just have easily meant for her to do what she did. She looked at the clock, and decided she could afford to write a few notes to correct this in the future.

Momo Yaoyorozu's Quirk will mutate and obtain a new function. She can lactate any liquid within her breasts without using fat cells, but at the cost of making them very sensitive. She is embarrassed by this unexpected mutation and only shares this information with Mina Ashido, and asks her for help in practicing with it in secret.

Looking over her work, she grins before closing her new book. She then went and finished getting dressed, pocketing her reality book in her bookbag. Who knows what other kinds of fun she could have over the course of the day...