You put it on for her

You agree. The big, genuinely happy smile all over her face makes it already worth it.

She puts it on your now flaccid dick, clicks and its locked. It can not be taken off without a key, or without ripping off your balls. You ask her how to remove it, she says, with the key of course.

You: “Where is the key?”

Sister: “I have it, of course. If you had it, there would be no point of it in the first place, right? Now you are not tempted to touch yourself and destroy our progress. And only I can release you, whenever you are ready for the next step.”

You dont know how to feel about it. The following day you keep on getting turned on by the memory of what happened with your sister. But every time you do, you feel terrible pain, as the tight little chastity belt has no space for expansion. Also your sister, whenever you cross her path in the house, gives you that weird, painful feeling. She winks at you, sometimes bends down in front of you, and when you start to scream from the pain, she laughs and tells you to think about premature ejaculation, just as you too discussed. It seems to make it worse. She says, of course, it takes a while to work.

3 days later, she grabs your hand and leads you into her room. She says you are ready for the next step. You get extremely excited. Finally she frees your dick. What a relief!

She asks: “So brother, are you ready for the next round?”

You: “Yes!”

Sister: “Ok. Last time you lasted 2 minutes. This time, you need to last at least 3 minutes, or I have to lock you in the belt for even longer, ok?”

You: “How much longer?”

Sister: “5 more days”

Damn, that is a long time in this tight, painful device. But you really want to feel again what you felt last time! You need to feel it again. You want her to touch you, so bad! And of course…you need to make progress, for the anniversary.