He might do it for a bet. Just like some friends might bet on who can pull off a crazy stunt, his friends could have bet him that he can't dress like a girl and act the part for a certain period.
It could be part of a role - playing game within the fanfiction world. For example, if there is a new RPG - like event at school where students take on different roles, Izuku might choose to be a female character for a unique experience and to challenge himself.
There could be a plot where Izuku needs to disguise as a girl to avoid some villains. The villains might be looking for a male hero, so by dressing like a girl, Izuku can move around freely and gather intelligence on the villains without being detected.
A practical answer is Chapter 100, because it turns the idea into a concrete scene. The chapter opens with The barrage was about to die of laughter., adds pressure through Who would dare write a script like this!], and ends on Her eyes flickered slightly as she grabbed the hand..
The best chapter pointer here is Chapter 96, "Can't Easily Forgive the Scumbag!". It opens with Jiang Li's words seemed absurd, yet there also seemed to be a trace of... and closes on Xu Ling couldn't contain her soft sobbing, "How could this happen?.
Look to Chapter 93 for the clearest answer. It begins with Jiang Li looked back and saw several aunties linking arms, walking up the..., keeps building through The leader was indeed the aunt to whom she had read fortunes this morning., and lands on I did the same when I was young, and when my dad.
A practical answer is Chapter 98, because it turns the idea into a concrete scene. The chapter opens with Jiang Li listened to the end and didn't have much of a reaction, only..., adds pressure through Several shirtless men were seen sitting around a table, playing cards and..., and ends on That's.
A practical answer is Chapter 108, because it turns the idea into a concrete scene. The chapter opens with In a glamorous Michelin three-star restaurant, Su Yinwan and Shang..., adds pressure through Jiang Yan, "...." Did he chew 20 times just now?, and ends on Hey, I've been waiting for you for.
Chapter 47 is the strongest chapter-level answer because it starts from Qi is actually second???] [Did the production team make a mistake? and follows through on Qi is so excellent and only got 17, yet Jiang Li comes in with 22?.
The best chapter pointer here is Chapter 121, "Jiang Li Gains 5 Points for His Meritorious Rescue!". It opens with Seeing that Wen Jiaojiao's condition had improved significantly, Director... and closes on You're supposed to be a man who conquers mountains!] Experienced and....
The best chapter pointer here is Chapter 110, "The Plow Ox CP didn't even start before it ended". It opens with Jiang Li, carrying a wooden basin, walked over to the well. and closes on My parents died, and fortunately, Daddy found and took me in..
If you want the clearest chapter reference, go to Chapter 81. Early on, Qi Tianyu, who chose curry beef rice, received a piece of curry and a...; later, the chapter leans on Shu Yan was relatively lucky, she got a bundle of noodles and a bag of....
Chapter 49 is the strongest chapter-level answer because it starts from My phone!!!" Jiang Yan's roar echoed continuously through the mountains in... and follows through on Thinking this, Jiang Yan marched forward, pulled Jiang Li down from her....