Reverse image reveals nothing
>>347186
Looks like a Chaika hentai doujin, but Saucenao isn't picking it up, so it might just be from the manga. It's not out of character for that girl to say something like that.
Possible one of these:
https://myanimelist.net/manga/69377/Hitsugi_no_Chaika_kka
https://myanimelist.net/manga/78897/Gakuen_Chaika
https://myanimelist.net/manga/93506/Hitsugi_no_Chaika_Bangai-hen
Possibly not. It might just be the end of a doujin after all, but none of the doujin on Exhentai go beyond 20 or so pages, so. Hopefully someone that actually knows comes along, since no reverse searches on the image gave me anything.