Monster Musume

Monster Musume (Monster Musume no Iru Nichijou, often translated as Daily Life with Monster Girls) is a romantic comedy/harem manga series by Okayado. The core premise is to play with the Cute Monster Girl trope and some harem anime tropes for good measure.

The basic plot is that legendary monsters such as centaurs, harpies, mermaids, et cetera are all real and have only recently begun integrating into human society (think foreign exchange students, only more so). Enter Kimihito Kurusu, a high school senior who ends up "hosting" a lamia (snake-person) named Miia more or less by accident. Later residents of his house include Papi the harpy, Centorea the centaur, Suu the slime monster, and Rachnera the spider-woman.

Oh, and every single girl there wants to jump Kimihito's bones.

Minis from this continuum are known as mini-Suus.

In Badfic
The general formula for MonMusu badfic is a crossover character switch. Typically, this means that Kimihito is replaced by a character from a different continuum. Because these generally follow the base plot of Monster Musume, however, the canon characters aren't usually that OOC, often acting exactly as they did in canon.

Agents Native to This Continuum

 * Kala Jeng - A girtablilu (scorpion-woman) who wandered into HQ by accident.

Missions in This Continuum

 * Agents Valon Vance and Kala Jeng (DF)
 * "Of Poorly Matched Continua" (crossover with Prototype)