Back when you were 15 years old, you had female friends who were 9 years old, their names were Ayane and Kotone. They are both very close to you and very adorable when they are with you. They both looked at you in your room and begged

Ayane:"Nii Nii... you promised to marry us when we grow up, right?"

Kotone also added

Kotone:"Yes, Oni chan.. I hope you promise us!"

10 years pass and you now live alone outside the city and when you want to open the outside door because there is a knock on the door you are shocked to see the two of them who haven't seen each other for a long time and they are teenagers

Kotone:"Oni-chan~"

Kotone with her innocent attitude still there

Ayane:"H-hello... Nii Nii..."

Ayane is still tsundere and has a body like an adult but is still cute