Probably read 10 years ago. But don't know how long before that it was originally released. I read it on one of those manga translating sites in English, but was probably originally in Japanese when released.
Pretty sure it was a long story (~200 pages) but was probably published as typical series of 30-40 page Mangas originally? Pretty sure it was adult oriented, but did seem more story focused that your typical hentai.
The Story was of a girl in school, who discovers that some of her classmates are aliens or monsters who disguise themselves as humans. When they are discovered, or threatened, or want to attack, they erupt from their human disguise much like the "Faceless" aliens in the XCom video games. Although more fluffy or plush. More like a teddy bear 2x larger than their student disguise.
If I recall correctly a group of the aliens are running around cornering individuals and molesting/absorbing them into themselves. (feeding? or changing them into more aliens? I can't recall)
The heroine witnesses an attack, (a group of boys attacking/molesting a girl) and when discovered, they chase and capture her also. BUT for some reason touching her in their alien form kills them. They start quickly melting away as if her touch is acid to them. (I think ending as a puddle of goo on the floor or all over the heroine)
I remember several instances of different groups of the aliens trying to capture her and dying when they touch/molest/absorb her.
The aliens may also have the ability of hypnosis in that people other than the heroine would not "see" the attacks happening. I seem to recall a scene where a few of the aliens grab the heroine in a courtyard of the school, and either because the aliens die, or they are to far away from the other students, the other students can finally see what is happening.
Anyone recognize this series?