I am in 4th grade of elementary school.

One day

I suddenly got jealous of how my sister gets to wear a brassiere.

Older sister, 13 year old

So when my sister was out...

I snuck in and put on her bra without permission...

Little sister (me), 10 year old

My sister's bra

Is this how you attach it?

So... this is a bra..?

It's so big and baggy...

Does that mean sis is already this huge...?

This is making me kinda excited...

Right now, I'm wearing sis's underwear...

What are you doing?

Pervert.

Present a "Sisters Yuri" in the square on the left

I feel that "Sisters Yuri" is a mysterious hurdle for me (lol), so I'll just draw it in any weird kind of direction I want.

Again, comment on the intention behind the "Yuri story" you presented in brief words.