Koneko was stalking this human boy out of curiosity as he her senpai in school as he just does things to help as she follows him before trips and falls towards him but he catches her as her head against his chest

Senpai: Koneko you ok?

She blushing as she smells in his scent before backing away embarrassed

Koneko: Yes of course senpai!

Senpai: Koneko... call me F/n, I transfered here from America so it weird with the things I seen go with that word!

Koneko: Can you help me study for a test coming up?

F/n: When the test?

Koneko: Tomorrow... I been busy with club activities lately!

F/n: I actually have plans tonight, sorry Koneko.

Koneko: What are your plans if you don't mind me asking?

F/n: I actually do as it classified!

Koneko watches her crush walk away in a hurry as she continues to stalk him as he meets up with a little girl who excited to see him as they spend the evening together as Koneko furious before storming off

Next day at school

Koneko see F/n as she has a pissed of cat vibe and she approaches him just to punch his gut and walk away as he unconscious from the force she used

Koneko: Stupid emotions!

Koneko continues her day as F/n in the nurses office as he heads home with Koneko stalking him as he meets up with that girl again as Koneko licks her lips at the idea she has as she follows her home and waits for her to be asleep to act as she sneaks in as she finds the girl hooked up to machinery at night as she strips naked

💦👶

Koneko unhooks her from her machines and strips her naked before sliding her feet first into her pussy as Koneko using her Rook trait to power through it as she moans when she gets rid of the girl as Koneko listens to snoops around carrying a living person in her womb as she finds letters from her crush as she finds out that the person inside her is his sister

Koneko: Oh satan... I messed up!

Koneko tries to birth the girl but her body doesn't budge causing her to grab her clothes and flee to get rid of the crime as she doing lewd things like masturbating to melt her down but she regressing her to a unfertilized egg and when she start getting tired her belly almost flat but her breasts grew in size

Next day

Koneko avoiding F/n for what she just did as she see him depressed as feels like she needs to comfort him but he gets up to leave before she could talk to him as she to blame before feeling something wrong with her body as she having flashes and hids in the nurses office as she see F/n here

F/n: Koneko you ok?

He see her embarrassment but she pounces on him as she hugs him

Koneko: I'm sorry!

F/n: Koneko... why are you apologizing for? That a hell of a punch, damn!

Koneko: That not why I'm apologizing... come by the Old School building after school, please!

Koneko leaves to the girl's bathroom as she moaning as she masturbates due to her hot flashes and picturing F/n shirtless

Later

Koneko before Rias as she looks down as the entire club comes in

Rias: Koneko... why are you telling F/n about the supernatural?

Koneko: Cause I did something... I killed his sister out of jealousy! I'll accept anything to attone my actions with F/n!

Everyone sits down as F/n comes in and scans the surroundings

Rias: F/n L/n... we need to have your trust that you won't speak of what you hear in here?

F/n: Sure Rias... I promise!

He sits infront of Koneko opposite side to her

Koneko: F/n.... I'm a subspecies of Nekomates called a Nekoshiso and I'm a reincarnated devil under Rias Gremory as her Rook.

Koneko reveals her ears and tail with her devil wings after standing up

F/n: Ok... so why did you apologize to me earlier?..... Also can I pet you?

Koneko: No.... cause you will hate me when I tell you what I did to you recently!

F/n: I saw what you did... my sister was one of those girls who fantasized about that... and the reason you couldn't get her out is cause you never gave birth!

Koneko and everyone looks at him as he blushing as Koneko sits on his lap

Koneko: Then why were you depressed?

F/n: Koneko she actually a unfertilized egg in you... and she wanted her big brother to be her daddy as she was terminally ill.

Koneko: You... and I have... a baby?

F/n: Yeah... she weird but I loved her!

Akeno: So Koneko... want to blank his memories?

Koneko: F/n... do you want me as her mom?

F/n: Koneko your cute and adorable... but yes eventually. Plus knowing your a pwetty little kitty makes it more cute!

Koneko soon feels her head being petted as she leans close to her mate as Rias coughs

F/n: Your secret being devils is safe with me... but Koneko seem to be enjoying this headpet to much?

He goes to remove his hand but Koneko put it back as she glares into his soul

Koneko: Pet or punched?

Koneko head start being petted by F/n as she soon feel him touching her ears as she nya cutely as she falls asleep just to wake up in a unfamiliar room but warm as she see she being held by F/n as he sleeping as Koneko nuzzles up to him and returns to sleep

A few days later

F/n in the Occult Research Clubroom as Koneko using his lap as a cushion eating her sweets as Issei comes in and looks at her breasts

Issei: Did they get bigger or are the stuffed?

F/n: Issei... she can kick your ass, only warning don't piss her off.

Issei: Why are you letting her sit on you?

Koneko: My boyfriend! Plus he knows what are club about as he swore not to tell anyone.

Issei: So what he your boyfriend... does that means you have unprotected sex?

F/n: God...

After he says god every devil whine but Koneko receiving headpets from her boyfriend

F/n: no cause one that leads to teen pregnancy... and too were too young to take care of a child!

Kiba: Issei... best you sit down and keep quiet!

Rias steps out of the shower and explains about the supernatural to him aswell his scared gear as Koneko purrs as she getting kisses to her neck as everyone looks at us

Akeno: Koneko... I get you love him, but at home please!

Koneko: I know but I enjoy his touch with my perdicment!

Issei: What!?

Rias: Koneko pregnant while she not cause of a thing she did!

Issei: That explains her bo-

Koneko hops off her boyfriend's lap and leaves as she returns with brass brass knuckles

Koneko: Tell anyone and he'll hurt you!

Issei: But why?

F/n picks up his kitten as she smiles as he carries her away

F/n: Text me her pack locations I'll see she gets there!

Rias: She has her usual... she knows where!

Koneko gets out off her boy arms and teleports as he salutes the rest

Kiba: Seeya man!

F/n: I'm going home to slay casuals!

Akeno: Oh no!

F/n heads home as he feels he being watched as he quickens his pace as he enters his home he hopes on his gaming console to play his Call of Duty Blackops 4 in multiplayer with his three friends as Koneko comes in

Koneko: I'm home... I'll be in the shower honey!

Party: You have a girlfriend?/What the fucking Hell!/ Is she hot?

F/n: I'll cook dinner after this match sweetie!

Koneko: Rad... and your friend doesn't need to know about my figure!

Koneko heads to the bathroom as they load up one more game as they go hunters rocking the same loadout of Peacekeeper as they dominate the match by splitting into teams of two before logging off after the match to go get dinner started as Koneko comes down in long shirt practically naked underneath blushing

Koneko: Babe... can you fight?

F/n: Kinda... but against the supernatural I'm useless aswell if it a gang up!

Koneko: I notice you have a sealed room... what inside it?

F/n: Just a unused room so I locked it.

Koneko approaches F/n and hugs him as she looks up at him and they kiss eachother passionately before she goes to the couch to watch TV as he cooking as they eat a healthy meal and turn into bed as Koneko snuggles up to her mate

After the Rating game

The Gremory peerage watch Issei get his ass beat but stops when they see cloaking teen holding a Grimoire as Blue Lightning in their hand

Cloak: Riser Phenex, you tired killing me but your assassin failed... now you'll feel the icy touch of death?

Riser: Who are you?

The cloak figure looks towards the Devils as Koneko looks shocked

F/n: You saw me in the human world... but now you find yourself fighting a Mage of Ice, keeper of the Artic Grimoire, and your reaper.

Riser: Fine... I'm done with this weakling!

F/n: Phenex tears... you snuck one to kill the Red Dragon Emperor.

Riser see multiple spell forming as F/n eyes glow blue as the arena freezes solid as Riser body freezing

F/n: Ice Age of Lost time!

Riser freezes as F/n approaches the heir as he shatters the devil and everyone looks at him

F/n: You forced this on yourself Riser!

He opens his Grimoire and he turns to snow as he returns to his home as he puts his mage attire and Grimoire back in the sealed room as Koneko enters with everyone

Koneko: Your a mage... how could you hide your mana?

F/n: My Grimoire... allows the user to tap into any type of artic weather, I  inherited from my mother... she died after she became a Witch and named me her successor. I sealed my mana in the Grimoire to appear not as a threat. I haven't swore the oath so I'm just a unregistered mage so Koneko until I swear the Oath we can date and be together.

Koneko runs up and kisses her mage as everyone leaves to let them be a couple as Koneko wakes up in bed with her boyfriend as nothing happened last night and they head to school but they meet up in the janitor's closet as they blush at eachother before heading inside as Koneko strips naked as her boyfriend does the same

❤

Koneko feels her body being kissed and fondled by her boyfriend as she purring before she lifted up to eye level and they share a passionate kiss while her nether lips are penetrated by his member as she starts moaning while he thrusting into her pussy as she continuesly moan as she reveals her neko heritage and gets more involved as she purring

Koneko: Don't stop... flood my insides... I'm almost close myself!

Koneko cums as her womb gets flooded with her mate's seed as she purrs satisfyed as the egg now fertilized as they continue with them fooling around as Koneko limps to class with a satisfied smile on her face as she glowing throughout the day while everyone thinking who her boyfriend as F/n reading the Grimoire as he recite the oath to inherite the full power of the Grimoire as he helps the Gremory peerage as Koneko with a bun in the oven as he fills in for her as her Mage in events and when their baby born Koneko see his sister in her with Nekoshiso trait during the home birth as she has traces of artic magic in her hair and they eventually marry after the defeat of Trihexa and live together raising the next generation of Nekoshiso and mages at a shrine in the mountains