After hugging and pouring her thoughts out, Alya stands up and stares at Yuki seriously.
"...What is it?" Yuki asked, worried if Alya took offense to her encouragement earlier.
Yuki realizes that maybe asking the girlfriend of your brother to consider your baby with him as hers after she lost her unborn child is a bad move, especially that now Alya has a stronger, prosthetic body along with only having part of her brain.
Aida quickly responds, "Host wish to understand why you cucked her and slept with your own brother."
Masachika stares at both Yuki and Alya and starts sweating profusely. He knows this might not end well. But at the same time, the opportunity of actually having more than one woman excites him greatly.
Yuki quickly retorts "Because I love him too. Won't you do the same if he dates someone else instead?"
Aida replied, "Host wants to tell you that you might have a point there."
Masachika's jaws slightly drop open, staring in disbelief at how easy it is to convince Alya for polygamy. He wonders if it has anything to do with her missing brain part.
Yuki sits on the edge of Masachika's bed and pats her swollen pregnant belly gently with her right hand, while supporting her body weight with her left hand. She begins telling them everything about her decision.
"I... wasn't feeling any different when I decided to let him knock me up."
"I was feeling lost, regretful, and unworthy for missing him out when you two are happily dating."
"Back then, just one day before we graduated..."
"I was staring at the ceiling of my dark room. I was... unable to sleep, anxious and worried about my life after graduation."
"I never had any actual feeling towards anyone. I asked myself if this is how a human should live."
"But everyone around me with the exception of my grandpa treated me like I'm alive..."
"So, I come to the conclusion that I do have some feeling towards others, it's just that I never really recognized them properly, all thanks to how my grandpa raised me and expected me to act."
"And... when I filter through how I feel about everyone... Masachika comes to mind first."
"He left the biggest lasting impact on me. I always try to reach up to him. I always think of him first. I was the saddest when he left Suou family to accompany dad..."
"He never stopped caring about me, and I haven't stopped caring about him, too."
"I finally realized... He is really my everything."
"I also realized... I am going to lose my beloved brother... again..."
"This time, it will hurt far more, considering what I have realized from myself."
"That's when I knew, I have to reciprocate it, and secure it before it's gone... No matter what."
"But the next morning is the graduation day already. He will go somewhere far away with his cute, non-blood related Russian girlfriend for college."
"So, I decided to go double, triple, and quadruple down on the plot of an incest porn doujin I once read."
"I checked my period tracker and found that the graduation party is the perfect time for my plan."
"Which is, make him knock me up and bind him to me for life so he can't get away from me."
"I kept telling myself that this is just another gacha roll for him, a limited rate-up event for him to get an SSR character and land a critical hit within my womb."
"Heh, I keep making excuses to myself, knowing it's wrong."
"Deep down, I know this is both incest and rape... yet I still want to do it."
"I threw away my reasoning, societal norms, my family, my parents, all just to try getting him."
"If he takes responsibility, I get a happy family. Twisted, but happy nonetheless."
"If he doesn't... Worst case scenario, at least I will still have my baby with me. I will always have a piece of him with me, and I get to have a kid that I'll raise to never leave me."
"So, I told Ayano to purposefully switch the drinks with alcohol and reserved a hotel room in advance."
"I didn't drink much so I can stay sober, of course."
"Once we were all there... Even though everything is going smoothly with everyone drunk and tipsy, I began to have second thought..."
"...Until I see Alya starts sucking your cock and riding it cowgirl style, saying that it's what you both usually do anyway."
"How do I say it... For the first time, I got fires of jealousy burning hot in my heart..."
"I didn't even think about how Masachika will get into trouble later. I just don't want things to end between me and him like this after the graduation party."
Yuki wraps her arms around her own chest with a soured expression and teary eyes, pouring everything she has in her heart out. "Once Alya was satisfied and fell asleep beside him, I just... lost it all. I gulped a whole bottle of wine and take my clothes off."
"I still remember... It was scary but also thrilling and exciting..." Yuki said while groping herself. "I masturbated... and fingered my pussy... until it's super wet and ready for his cock..." She said while imagining vividly the depraved act of incest rape she did back then to her own brother, who was laying down right beside his girlfriend.
"Ah... I never even masturbated before to porn, and yet I'd do anything just to get knocked up with my brother's baby... I'm a fucking lost cause..." Yuki said as her body warms up. She strips her clothes again, trying to get her orgasm off as quickly as possible from pleasing her brother's eyes, letting him feast on her aroused pregnant body. "That day, I finally realized why I always come to his bed in the morning to tease him... I like his manly scent... Ever since I hit puberty..."
Yuki starts caressing her pregnant belly while flicking her erect clitoris while recalling the time she lost her virginity to her own brother. "Ah... I just... Can't win against my first feeling of horny and... I just threw away my maidenhood to him... I could never regret that decision I made..." She said as her pussy starts getting wet, gaping uncontrollably around nothing, hoping to feel her brother's dick again inside her.
Yuki shivers as she recalls the pain of her defloration "Ah... I just thrust my hips down and his fat cock rips through my hymen like it's paper. It's fucking amazing..." She said while drooling and masturbating in front of Alya and Masachika who's listening to her story. "This lewd body... this pregnant belly... it was all your cock's fault, brother..." She said while showing off the proof of her depraved act long ago in front of them, her swollen late-term pregnant belly. "Your cock awakened my inner slut... I just... love it so much, brother... I didn't even feel the pain from being deflowered because I was so horny and desperate!" She said boldly and truthfully to him.
"Alya... Mnh... You know how good is it to get knocked up... by the man you loved, right? Ah... Can you really blame me?" Yuki said while continuing to masturbate in front of them, shamelessly showing the couple in front of them her dripping wet and gaping horny pussy from remembering how she let her brother's cock deflower and knock her up. She moans and shivers uncontrollably as she remembers how Masachika's cock made her a slutty woman for real.
Masachika can only gulps upon hearing his sister's lewd action and words. On one hand, she has done a depraved immoral thing. On the other hand, his dick starts to get hard and his lust is stoked ablaze again.
Alya's gaze wanders at Yuki's masturbating figure, and then her sight is set Masachika's erect cock. She can only conclude that both of them are attracted to each other.
Aida then conveys her message "Host Alya wants to know if Owner is interested in polygamy and incest."
Masachika replied "...This little gremlin is making me unfaithful. I wouldn't even want any of you to sleep with someone else but I... I'm sorry for being a cheating boyfriend, Alya..."
He then proceeds to defend his sister "I can't really blame Yuki either. Her affection and problems are all genuine. If she wanted you dead, she could have done nothing. Instead, she saved you."
Yuki adds "Yes... Ah... I really... care about big bro's... happiness too... And I... don't wish you harm..." while rubbing her twitching pussy with her slender fingers.
Alya, despite missing some part of her brains, understand the circumstances, and proceeds to deliver a shocking message to them.
Aida conveys her message "Host has given her approval and blessing for a polygamy. Please take care of us."
Masachika's jaws dropped even harder "What the fuck...? Alya, are you serious!? Think about it more! D-do I need to get your other brain part first?!" He says in shock and panic.
Yuki grins with satisfaction, seeing her persuasion was fruitful "Ah... thank you very much, Alya! From now on, let's serve his cock together!"
Masachika then realized that the sexbot AI core is messing with Alya's judgment as it tries to make her equally horny as himself according to its protocol.
But, he decides to keep it to himself, seeing it as a chance to actually being a present father figure to Yuki's child, as well as a chance to also have Yuki available for him to sleep with.
"...Okay then." Masachika says, accepting Yuki as his girlfriend.
Yuki exclaims "It's settled then!" as she wraps both Masachika and Alya in her arms, pressing her breasts and swollen belly against them. "I don't mind being a mistress or just a cumdump as long I can be with you, brother!"
"...Yes, someone from Suou family and Central Cabinet even act shamelessly like this thanks to your cock, brother." She said while grabbing his cock head "It's been so fucking long... I miss this dick so much..." Yuki said shamelessly, revealing her true inner slut after being away from Masachika for months. "Hah... I love you, my brother. Thank you for leading me to this very moment, destiny... The alien invasion, big brother's baby, and the circumstances regarding Alya..." Yuki told them both, thankful for their understanding.
She lays down on the bed with her hips raised and her labia spread, showing him "Please, fill this fuckhole of mine that's been shaped and molded by your cock..." Yuki begs him, not caring about anything other than being fucked silly with his cock right now.
"A-are you sure? Won't it hurt the baby?" Masachika asked her, trying to be considerate for everyone involved.
"Don't worry about this baby. It should be strong like you, and there's Aida here in case anything goes wrong. and... I really don't mind if you want to feed this baby some of your jizz." Yuki said while grinning. She then makes another crazy depraved claim to entice his brother even more "If it's a girl, I'd even raise this baby as your daughter-wife if you are into it."
"Fuck... you are way too lewd to be my sister! Alya, hold this wench down for me!" Masachika said to Alya, which immediately hold Yuki down with great precision, while monitoring her pregnancy.
"Go on, my brother. Stick your stiffy into my pussy and fuck me properly... Make me pay for teasing you and stealing your cum back then!" Yuki said moments before Masachika grab hold of her waist and fuck her pussy inside out. At that moment, he realized that Yuki was not exaggerating about her pussy having taken his cock's shape. It fits like a hot glove on his cock, wrapping it with its tender and soft slimy vaginal walls, gripping it and milking it for all it's worth.
Yuki squirted and orgasmed hard just from few thrusts from him. "AHH! I MISSED THIS SO MUCH! UHHH! COME ON, BREAK ME, BROTHER! UNF... I DON'T FUCKING CARE ANYMORE! MESS MY PUSSY UP! RUIN IT SO NO ONE ELSE CAN CLAIM ME!!!" She said while locking her waist with her legs. "MAKE ME UNABLE TO LIVE WITHOUT YOUR COCK!!! IMPREGNATE MY WOMB AGAIN IF YOU CAN!!" She screamed, wishing to spawn as many babies as possible using her brother's sperm.
"FUCK... AHH! SORRY, MOMMY JUST CAN'T HELP HERSELF! MOMMY MISSED DADDY'S COCK FOR SO LONG! DON'T MIND HIS COCK KNOCKING ON MOMMY'S WOMB!! AHHHH!!! I'M SORRY FOR BEING A SLUTTY MOMMY!" She screamed at her own pregnant belly, hoping her unborn child would forgive her for putting it in danger as she orgasmed again from the condition.
"Yuki you damn degenerate... you pregnant whore... you purposefully... quote from the porn I often read long ago!! You sly bitch!" Masachika called Yuki out as he grinds his cock even more. Then, by complete chance, his cockhead stimulated Yuki's G-spot, making her orgasm and squirt copious amount of love juice to her brother. "FUCK FUCK IT'S COMING HARD!!! MY G-SPOT!! FUCKKKK!!!!" She screamed while arching her back and shivering all over. Her maternal instinct is in overdrive and her pussy keeps twitching uncontrollably around his dick, trying to get herself pregnant again even though she obviously already is. Her legs keep locking his waist, wishing for him to give her a creampie.
After 10 minutes of pounding Yuki's pussy, Masachika finally approaches his orgasm. "Yuki... I'm going to cum soon! Are you really sure it's safe to cum inside!?"
"Ywess... Do it..." Yuki answers weakly. She is exhausted from having constant orgasms, trying her best to stay conscious.
"UNGGRH!" Masachika grunted as he ejaculated deep inside his sister's pussy without remorse, his cock twitches as it shoots thick ropes of semen into her cervix in vain.
"AHHH! FUCK I CAN FEEL IT SPURTING INSIDE ME! I LOVE YOU!!!" Yuki screamed as her legs pull and prevent him from pulling out. She can feel his cock spurting hot jets of sticky and creamy load inside her pussy.
Alya stares at their act of love making intensely, trying to learn Masachika's preferences and weak spots as her sexbot protocol by Aida dictated.
"You still got it, stud... But... I don't..." Yuki said weakly as she falls asleep due to exhaustion.
Masachika soon fell asleep beside her, exhausted due to long day of work, staying up all night, and having sex with both of them.
Alya, who no longer need to sleep, covers them both with blanket as she stands nearby all night long, wondering where this relationship will take them.