A school girl gets chloroformed by one of her classmates, named Shizuka. While being chloroformed, the girl attempts to elbow Shizuka in the stomach, but it doesn't work.
Keywords: school girl, loli
Source: exhentai.org
A bunch of people gang up and chloroform a girl named Megumi.
Author: [Yanagi Masashi]
Original title: 恋愛悪魔
Light hearted ecchi menga
English version here: https://hentai2read.com/renai_akuma/
The main female protagonist is chloroformed by a gang, in a scene that lasts several panels. Another male is also chloroformed shortly after.
This was a rather violent manga too.