Taimanin Asagi 3

A 2016 Hentai anime, Taimanin Asagi 3 is an adaptation of the visual novel of same name. It was released as a two-episode OVA between 2016 and 2017.

The anti-demon ninja Asagi has taken to herself the role of raising the brother of her deceased lover Kousuke. Kousuke, however, has less-than-holy feelings for his adoptive mother, and uses his special powers to make her aroused. Despite deeming their relationship "forbidden", Asagi nonetheless engages on a secret relationship with him after he uses his powers on her and she enjoys it.

When being sent away on a mission, however, Asagi discovers the entire mission had been a distraction to keep her away from Gosha Village. Murasaki and Sakura are captured and raped by Edwin Black's troops, and her son/lover Kousuke has been transformed in a fragile humanoid-ball of flesh, given to Oboro, one of the subordinates of Edwin. Seeing the boy which she raised and loved with his life threatened, Asagi surrenders to Oboro.

Animated by Studio Eromatick. Produced by ZIZ Entertainment. Directed by Shinpei Kasahara.

Tropes used in Taimanin Asagi 3 include:

Absurdly Youthful Mother: Asagi doesn't look that much older than her adopted teenage children, Asuka and Kousuke.
Adaptation Distillation: Seeing as this is an OVA adaptation of the Taimanin game with the longest story, this was unavoidable. The first episode alone skips over almost half of the events that occurred during Asagi's route in the game.
Back-to-Back Badasses: Sakura and Murasaki in the first episode when they were fighting off an army of armed soldiers, until the Japanese army robot shows up.
Bait and Switch: Near of the end to the second episode, Oboro said "Today, I brought the person most important to Asagi." Which at first seems to refer to Kousuke but turns out to be a green orc, which she supposedly married.
Balloon Belly: Asagi suffers this at the beginning of the second episode when she was being raped by some Naughty Tentacles.
Brainwashed and Crazy: Sakura and Murasaki in the second episode.
The Bus Came Back: This is Murasaki's and Edwin Black's first OVA appearance since their last appearance in Hell Knight Ingrid.
Cannot Spit It Out: Thanks to the parent-and-child relationship they have, Asagi and Kousuke are reluctant to talk to each other over their feelings.
Cliff Hanger: The series ends with Asuka swearing to save Kousuke, with his and Asagi's fates unclear.
Distressed Dude: Kousuke was turn into a meatball by Oboro and, who is literarily holding him hostage.
Happily Adopted: Kousuke and Asuka were adopted by Asagi at some point before the start of the OVA, and both clearly love their adopted family. However, Asuka decides to go off on her own to save her stepbrother after refusing to help Asagi in the first episode.
Marshmallow Hell: Sakura sticks Kousuke's head between her breasts while teasing him about his attraction to Asagi.
No Sympathy: In the second episode Asagi is raped and transformed into a sexual slave, Asuka doesn't care about this and hates her, because she failure in save their stepbrother.
Not Blood Siblings: Kousuke and Asuka. Assuming that OVA follows the visual novel's storyline, Asuka is sexually attracted to her stepbrother.
Parental Incest: Asagi engages on a carnal relationship with her adopted son.
Speed Blitz: Asagi finally demonstrates her unique ninja ability of Super Speed when tries to kill Edwin Black in the second episode. Sadly, it doesn't work.
She's All Grown Up: Due to the large time skip between TA2 and TA3, Sakura and Murasaki go from being teenagers to being in their mid-20s.
Snap Back: Even though the TA2 OVA ended on a Downer Ending, TA3 is the continuation of TA2's Good Ending from the visual novel.
Take a Third Option: In the second episode Asagi must choose between the life of Sakura and Murasaki, or the life of her boyfriend. She decides to attack directly Edwin Black, only to be easily defeated.
The Worf Effect: Sakura and Murasaki are easily defeated by the PX-887 Kai Raiden, just to prove how dangerous the robot is.