Been wanting stories focused on a monster girl app that leads to unforeseen consequences
>MC finds the app one day and uses it to turn his other shy and insecure friend into a succubus
>Both of them check out the succ'd friend's naked body, causing her to unintentionally use her innate seductive powers
>MC ends up losing all sense of control, hops on her and fucks her like an animal in heat
>Ends up having enough life energy taken from him to knock him out cold, causing her to become addicted and gain newfound abilities
>She proceeds to take his phone and leave him a parting gift
>MC wakes up, sees a fledging succubus staring back at her in the mirror, and realizes what happened
>Now has to fight a more powerful succubus who could be any women in the city to turn back, while simultaneously not caving into her newfound sexual cravings

>Boyfriend and his bicurious girlfriend get the app on their phone
>Decide to spice up their sex life by trying to both turn into a random monster girl species mid sex
>As they both get close to climax, one of them activates the app without looking
>Both of them proceed to become slime girls
>The exotic feeling of transforming on top of everything else leads both of them to cum, causing them to lose any semblance of control of their new bodies
>This ends up causing both of them to merge into each other, both minds melding into one another synchronized by pure orgasmic bliss
>As the intense feeling wears off, the resulting slime girl realizes what happened, uses all of her focus to make her slimy hand take on the properties of a human hand, and hits the revert button on herself in panic
>She ends up turning into a human girl that looks like a mix of both the MC's sister and the girlfriend
>Freaks out, turns back into a slime girl, and tries split herself off into two and try again
>Split form ends up being mentally the same, with both their human forms being younger identical twins of each other
>Panic ensues further