Wear it with the sundress.

You cautiously check around the corner to see if your sister Rachel is still there. Confirming that the coast is clear, you swiftly shut the door and begin undressing, including removing your underwear.

You retrieve the panties and slip them up your leg, allowing them to conform to your shape. Releasing them, you feel the fabric against your crotch, causing a partial erection.

Your breathing becomes heavier as you wrap the bra around your chest, clasping it over your nipples, which brush against the fabric. Recalling how girls do it in movies, you reach around the back to fasten it.

Almost effortlessly, you manage to secure the clip on the first attempt. Your face flushes as the weight of your actions sinks in, and your penis responds by becoming fully erect.

Biting your lip, you then don the sundress, pulling it over your head. Once you're fully dressed, you become acutely aware of the vulnerability of your lower body.

Following your sister's suggestion, you have shaved your entire body. You feel the breeze against your legs, an unfamiliar sensation that extends to your chest.

Not to mention, you're wearing a skirt as well. It feels strange to have the air gently brushing against your buttocks. However, you haven't had a chance to see yourself in the mirror yet...

You bite your lip, your heart racing. Slowly, you turn to face the mirror and are greeted by the reflection of a cute girl. You stand there, stunned, taking several minutes to process that the person staring back at you is indeed yourself.

Reaching out your hand to touch the mirror, the unknown girl on the other side mimics your actions. Flustered, you can't help but giggle at the realization of what you're doing.

However, upon hearing your own giggle, you instinctively cover your mouth. Why does it sound feminine? Is this all coming naturally to you?

"I-I um..." you start to speak, but a noticeably more feminine voice escapes your lips. You quickly close your mouth, your face turning red. Perhaps it's because you're crossdressing as a girl.

Everything, from the makeup to the lingerie and dress, feels strangely natural to you, almost like second nature. Even altering your voice seems effortless.

The final revelation comes as you gaze into the mirror. You undeniably look like a girl...

Before you can delve deeper into this realization, a knock on your door interrupts your thoughts. "Hey, Ash, it's about time to head..." Your sister's sentence trails off as she walks in and looks at you.

Feeling embarrassed, you fidget with your hand, unable to meet her gaze. Suddenly, she squeals in excitement, rushing over to hug you. "AAAAA! Oh my gosh, you are so adorable! You're going to rock it out there!" she exclaims with delight.

Then, she glances at you with a mischievous smile and pulls you into a tight embrace, catching you off guard. In that moment, you feel her hand firmly on your buttocks.

A slight moan escapes your lips as her touch ignites a pleasurable sensation. "Ah~"

Whispering into your ear, she teasingly asks, "Are you enjoying my underwear, you pervert?"

She then grabs hold of your erect penis, licking her lips as she watches you squirm in place.

"I had no idea my brother enjoyed wearing his sister's panties," she remarks, bending down to observe your erection protruding through the dress. Playfully, she flicks it, sending a jolt of pain through your crotch.

Instinctively, your hand moves to protect yourself, causing your penis to shrink back down to its normal size.

“That should deal with that! Anyways come on I’ve already got the car started.” Rachel says while dragging you around. Still stunned by the pain.