A polite but serious advisory; don't do this IRL; it could be considered as leading to rape (even if it's female raping male). That said, back to the fantasy.
Shiki-nyan's *cough-cough* "special herb tea" (Page 2) seemed to be Super-Effective in what it did to P-kun (the Lucky Bastard). Conclusion: "Ah, What A Fine Day For Science!" And I look forward to the (a-hem) continuation of this series.
Woah, very effective drug! In real life, such scenario is rather depressing because the victim usually doesn't have that much fun and at least one of the participants would have problems to deal with the aftermath.
It's disappointing that the original scans have so much jpeg artifacting, but there's not much you could have done (I'm not sure what this community thinks about using Waifu2x just to remove noise).
I can't say no to a Ichinose Shiki story though! Hopefully you'll get to translate the sequel as well!