It's late at night when my phone rang, it's You. Weird, I haven't heard from her since the joint swim meet, what could she want now?
"Hello?"
"Hey, are you a good teacher?"
"I don't know if I'd say that, I've helped people in class befo-"
"That's good enough. I need you to teach someone to swim. Are you free tomorrow?"
"Yes, but why can't y-"
"Perfect, meet me at the community pool around 1. See you there."

12:50, sitting at the pool. To be early is to be on time right? Suddenly I heard You's voice.
"Wait here for a second okay?"
Who is she talking to? No matter, her silver hair comes through the gate and she puts her finger over her lips. Why do I need to be quiet? What is she planning?
"Listen, go hide until I tell you to come out."
"Wha-"
"Do it. By the way she's a complete beginner so make sure to stay very close to her."
She ran off again, why am I putting up with the antics of a girl who I barely know? Hidden from sight I hear her coming back through the gate, this time there's a second voice.
"I-i can't swim, so g-g-go easy please"
"Sure sure, no problem Ruby"
Suddenly the gate slams close and the lock clicks
"Alright, come on out!"
I emerge from my hiding spot and see the girl she was talking to. An extremely small girl with green eyes and red hair who looks like she's on the verge of tears.
"A-a-a-a-a b-b-b-b-b-b-b-b-b-b-b-b-b-b-b-b-boy YOU LET ME OUT LET ME OUT MARU HELP ME"
"You'll need to be comfortable around boys if you want to be an idol Ruby. I'll be back in a bit. Yousoro!"
The red headed girl is in tears and I'm afraid to try talking to her.
"Ruby, was it?"
She screams "MAAAAAAAAAAAAAARUUUUUUUUUUUUUUUUUUUU HELP MEEEEEEEEEEEEE"
Why did I even agree to help You? Come to think of it I never agreed at all.
"Listen Ruby, we're going to teach you how to swim, okay?"
She won't stop screaming. Who the hell is Maru anyway? Why am I responsible for this baby?

15 minutes later, she seems to have calmed down, time to take the initiative.
"Ruby, let's get started with the swimming lesson"
"..."*sniffle*
I jump in the pool and signal for her to head to the steps. She seems to be moving towards the steps, although very slowly, and I can tell she's saying something but can't tell what. As she gets closer I can make out
"this is for aqours this is for aqours this is for aqours"
What the hell is Aqours? Whatever, the sooner I start this lesson the faster the time will pass until You saves us both.
"Alright Ruby, slowly walk down the steps. Take your time and be comfortable."
Now that she's closer and stopped bawling I start to appreciate how cute she really is. Her delicate feet penetrate the surface of the water, quickly retracting at the temperature before she submerges them again. As she gets farther in you see the water flow around her perfectly smooth thighs and splash up against her tight little stomach, eventually reaching up to her small, firm breasts.
What am I thinking? This girl is a complete crybaby, I want nothing to do with her.
At least she's not afraid of the water, I guess she just needs help with actual swimming.
"Alright Ruby, now grab my hands and we'll practice your kicking."
"O-o-o-o-okay"
I put out my hands but she won't take hold.
"Come on Ruby, I won't bite."
She starts muttering under her breath again, but at least she's extending her hands. I grab those petite hands and am amazed at how smooth they are.
"Alright, now pick your rear legs off the ground and start kicking."
She doesn't budge, guess I need to give her some help. I put both of her hands into one of mine and use the other hand to push her legs off the ground. Her thighs do feel really nice.
She panicks at first but then starts kicking and calms down, well at least calm for her. I slowly start leading her around the pool and she seems to be doing fine.
"Alright Ruby, I'm going to move my hands to underneath you so you can practice your arm motions
"o-okay"
I move my hands to underneath her, she's so short I needed to be careful I actually put them on her stomach and not her chest. She seems to be doing fine though.
"How are you doing"
"g-g-good"
"Alright, now I'm going to remove my hands. Just don't think and keep swim-"
"NO"
"Okay okay"
A couple minutes pass and I ask again.
"Can I take away my hands now"
"U-u-u-u-u-uh"
Not waiting for her response, I slowly remove them so she doesn't notice.
Bad idea. She starts panicking and goes under. I dive down and grab her, picking her up by her supple armpits.
"Are you okay?"
Holding her above the water she catches her breath
"y-y-y-y-y-y-yeah"
It's at this point, as I'm holding her in my arms, the gate reopens and there is not only You, but also an older girl with jet black hair.
"You, how dare you leave Ruby alone with a strang- GET YOUR HANDS OFF MY SISTER"
The black haired girl jumps in the pool, fully clothed, wrestles Ruby out of my arms and rushes her out.
"Come on Ruby, we're going home"
and like that, they vanished.
"So how did the lesson go?" You asked
"Who knows, I told you I wouldn't call myself a teacher"
"I'm sure it was fine. Later!"
I never should have given that girl my phone number.

Later that night my phone rings. It's You, again. Do I dare answer?
"Hello?"
"Hey, are you free tomorrow?"
"Why?"
"Ruby said she wants another lesson"

"Yes, I'm free"