Yes, you can certainly last 3 minutes now.

Yes! You can’t resist.

Sister: ”Great! I figured its time for the next step. Your dick needs to get used to the warm wet feeling that a pussy will give you. Otherwise you will never last. My spit last time gave you a heart time, but its not quite the same sensation, its not as slimy as the real fluid of a vagina.”

You don’t know where this is going, but you are very intrigued. She sits in front of you, her legs spread, and looks you in the eyes with a naughty look that you haven’t seen before on your little sister. She takes her right hand and slowly slides down her flat belly, right into her pants. You watch in awe. And you instantly get semi-hard.

She starts to move her hand around in her pants, while starting to breath heavy, then moaning sensually. You get completely hard. While doing that, she tells you between her breaths to not get too excited yet, as this is not part of your stimulation yet. She tells you, to keep your lust down, until she starts with you, you should do your little trick. You imagine, as always, how you cum prematurely, but it doesn’t make you any less horny.

You: “It doesn’t work!”

Sister, between her breaths: “Say it…out loud!…I have to hear…..maybe….you…do it…wrong!”

You think, alright, you dont want to discuss with her while she is touching herself. Watching her turns you on so much, even though its totally wrong. You cant say no to anything she asks now.

So like a good boy, you start to describe to your sister what you are supposed to think of to stop yourself from cuming. You describe how you are about to enter a pussy, and the moment you feel her wet and warm inside, you feel your orgasm approaching…You just start fucking her and you are already so close, long before she could be satisfied…You cum uncontrollably after just getting started, and the girl laughs at you, is shocked, and disappointed..

Somehow you are even harder now…at he same time, your sister breaths heavier, apparently getting hornier with every word…making an incredibly sexy moan, the moment you say “cum”, “laugh”, “disappointed”..and “premature”

Then she stops. She slowly takes her hand out of her pants, and you see that her fingers are covered in a clear, thick fluid. You notice a beautiful smell, that you never smelled before and that somehow turns you on.

Your sister really…actually…moves her hand closer to your dick…and touches it. Her thick pussy juice runs down your dick and she starts to jerk you. The sensation is like heaven on earth.

Sister: “Dont forget, 3 minutes at least, or its 5 more days in chastity.”

You get nervous. The sensation is too good. You are too horny right now. Your sister notices and tells you to use the trick again. To tell her about premature ejaculation. You start talking, start describing how you are about to enter a woman, when the sensation overwhelms you! You cant stop. You sister yells: “No not yet! Its too early! Dont cum yet! We just got started!”

But you cant stop yourself. You explode onto her. She smiles, licks her fingers and gives you a kiss on your cheek, while the ‘click’ sound tells you, that you lost, and youre back in chastity.

1.5 minutes, less than last time. “Why am I worse than last time?”

Sister: “Well brother, thats the magic of pussy juice. It feels much more intense than saliva. My hand covered in pussy juice is much closer to the feeling of a pussy then what you had last time.. Good that we made this experiment, next time, Im sure, you will last longer, now that youre dick experienced it. But yes…we still have a long way to go.”

The next 5 days are painful. You can’t believe that you actually had your sisters pussy juice on your dick. You cant believe that you came for her, twice. Your anniversary is getting close and you hope you gain that stamina in time. Thank god your sister helps you. You cant get around noticing that you get more and more attracted to her. You secretly start to fantasize about her. Fortunately, these sick fantasies are ended quickly by the pain from the chastity belt, whenever your dick fills with blood.

After the 5 days, you come to your sisters room in excited anticipation. You are not sure what you are more excited about, finally getting freed from the device, or feeling your sisters hand on your dick again..

Sister: “Before we start, I have to tell you, I really expect some progress from you today. 10 minutes at least.”

You: “What if I wont make it?”

Sister: “Well, you know the punishment. This time, it will be one extra day with the chastity belt.”

You think nice, 1 day is absolutely ok.

Sister: ”I mean 1 day for every minute you cum too early!”

You: “What? The anniversary is in 4 days!”

Sister:”Then you better dont cum too fast ;)”

You: “Can we make it 5 minutes?”

Sister: “If theres no pressure it wont be effective. I need to push you!”

You: ”6 Minutes, please!”

Sister: “8 Minutes, thats the lowest I can go! No more discussion.”