NOTE: Timeline-wise this chapter takes place after the partner swapping in chapter 1, but before the Outdor Schoop trip and Epilogue.
SUMMARY: Shintaro continues treating Mei like his particular toy, though it's clear she's far from unwilling at this point. The first group scene introduces a new character (Takuya), childhood friend of Chie(glasses girl), who in spite of his girly looks is quite hung.
Second scene goes back to the sex practices and the other new character, Naoki(light brown hair) who enjoys stealing other people's partners. However, his display fails miserably here, as poor Takuya is quite busy being used by a now unleashed Mei.
Irritated, Takuya makes Mei his next target and puts some sleeping pills on her drink. His plan comically fails again, because at her current succubus level even a sleeping Mei turns out to be too much for him. Finally, his last resort (while grumbling that in that way doesn't even feel like netori at all) is to use hypnosis on her, but Mei is rescued by a -surprisingly- worried Shintaro.
*************************
Second compilation of the Sex during School's Lessons published by the artist in Pixiv. Though strictly not part of this compilation, I've included at the end the Omake content for Mei, as this one is mostly her chapter: