Majuu Jouka Shoujo Utea

A 2015 Hentai anime based on a 2012 manga series of the same name created by Suzu Suzuhane.

Mitsuki and Karen are two ordinary High School girls, until they're recruited one day by a mysterious creature to become Magical Girls and fight evil. To their dismay, they find out this actually means having sex with monsters to subdue their influence on society. They start the story being manhandled by the beasts over and over, before eventually giving into the pleasure and becoming "beasts" themselves - capable of growing sex organs of the opposite sex and using them to sleep with other girls of their choosing so the cycle may continue.

Animated by studio EDGE.

Majuu Jouka Shoujo Utea contains examples of:

• A Date With Rosie Palms: While seducing Karen in the shower, Mitsuki reveals that she always lusted after Karen even long before they became magical girls. She furiously humped a giant teddy bear Karen gave her for her birthday every single night while salivating over the thought of fucking Karen.
• Best Her To Bed Her:: Mitsuki attacks Karen and punches her so hard she sends her flying into a wall before beginning to seduce and fuck her. Karen eventually relents and begins going along with Mitsuki's desires.
• Bi the Way:
  • Mitsuki rapes Karen in Episode 3 after becoming a sex beast, with Karen eventually giving into the pleasure and reciprocating the affection. The significant part is that Mitsuki reveals she was actually always attracted to Karen, even before becoming a sex beast, and grinded on giant teddy bear she received from Karen to masturbate naked every single day. Mitsuki was already known to be interested in men, including her brother and father.
  • In Episode 4, Mitsuki and Karen recruit new girls to be sex beasts by having sex with them, and they quickly submit to their upperclassmen and become fixated on providing enough pleasure for Karen and Mitsuki to gain their approval. Both girls also routinely sleep with men to corrupt them afterwards.
• Bigger Is Better In Bed: Karen is initially horrified by the size of her first sex beast's penis, but after licking it and being exposed to aphrodisiac she goes whatever she can to it to pamper the beast. Despite the fact she and Mitsuki dread having to have sex with the beasts, they both end up finding the experience of getting fucked by them extremely pleasurable, in part because of how large they are.
• Breeding Slave: What the sex beasts want to make all women into. Mitsuki and Karen become magical girls to stop them, but this basically means that they have to let the beasts fuck them until they run out of energy so that they don't target civilians.
• Bring My Brown Pants: Karen urinates herself of sheer terror after being raped by a monster at the end of Episode 1, and begs to Curio she doesn't want to be a magical girl anymore.
• Brother-Sister Incest: In Episode 2, Karen is drugged by pheromones into seeing her brother and father instead of two sex beasts, and the two use the guise to fuck her. While initially putting up some resistance, Mitsuki quickly submits and actively enjoys herself, noting she'd rather have sex with them than the sex beasts (a big deal, given how many times she had already slept with beasts by that point - meaning she would have done so multiple times with her brother and father if given the choice). She ends up severely lusting over her "brother" and pleading with him to fuck her harder while gushing over how much she loves him.
• Crying After Sex: Both Mitsuki and Karen do this after their first time with the sex beasts. They eventually become tears of joy as they grow more aroused by the prospect of being fucked - for Mitsuki, this happens when she hallucinates having sex with her brother and father. For Karen, it's when she's fucked by Mitsuki.
• Expy: Curio is based on Kyuubey from Puella Magi Madoka Magica, a creature which at first seem similar to another Ridiculously Cute Critter mascots of magical girl shows but (spoilers for PMMM ahead) actually is manipulating teenage girls into taking a terrible path on their lives for their own ends, not caring what happen to those who do deals with them. In his first scene there's even a zoom on his pink, emotionless eyes, something which happens a lot of that series with Kyuubey.
• Extreme Libido: It turns out Mitsuki always had this, even before becoming a sex beast.
  • She was so horny that when Karen gave her a giant teddy bear for her birthday, Mitsuki would hump it like crazy every single night while thinking of fucking Karen.
  • When she's getting fucked by sex beasts pretending to be her brother and father, Mitsuki ends up getting turned on even more than usual and starts begging them to slam her harder.
  • After becoming a sex beast, Mitsuki assaults Karen and molests her over and over until Karen starts wanting to have sex with her.
  • Both Mitsuki and Karen become this after they sleep with each other, and are so horny they kidnap two new girls and get them to suck them off to transform them into sex beasts as well.
• Flashback: Mitsuki has a flashback of the night after Karen gave her a huge teddy bear in Episode 3 - and is shown to be using it to masturbate while pretending she's having sex with Karen.
• Huge Guy, Tiny Girl: The sex beasts that Karen and Mitsuki are forced to sleep with all massively outclass them in height, weight, and girth. Karen's first sex beast has a member as large as her arm, and both girls are basically treated like ragdolls as they're fucked by the beasts. In Episode 2, Mitsuki is gangbanged by two sex beasts pretending to be her brother and father, and their much larger size allows them to pin Mitsuki in place or easily carry her while they double penetrate her.
• Love Potion: Zigzagged in the sense that in Episode 2, while Mitsuki is drugged into seeing her brother and father instead of sex beasts, her desire to fuck them and enjoyment of the experience isn't a result of the drug - she just rationalizes that she'd rather be fucked by them than sex beasts, and decides to enjoy the ride.
• Making Love In All The Wong Places: When having sex with a sex beast, a barrier forms around the beast that spans several blocks, and makes the area invisible to anyone in the vicinity. In other words, it allows sex beasts to have sex in public without being seen - something Mitsuki and Karen initially find very distressing, but ultimately take advantage of themselves after they become sex beasts.

• Proud Beauty: After her transformation into a sex beast, Mitsuki is way more dominant and deliberately dresses in the most slutty way possible to attract attention. She really plays this up when trying to seduce Karen. Both Karen and Mitsuki are also quite satisfied when they end up having two younger girls drooling over them and sucking them off. These girls also become quite confident of their sex appeal after this encounter, using it to entice men for to spread Mitsuki and Karen's influence.
• Sensible Heroes, Skimpy Villains: The costumes Mitsuki and Karen wear as sex beasts are way skimper than their magical girl outfits.
• Slasher Smile: Curio smiles like that after telling his plan to turn pubescent girls in sex beasts to Karen in Episode 3.