"Since it's winter and you've fed up with your parents, they'll take you to your grandparents' house, where you'll be able to enjoy the Japanese winter."

Your grandparents are Kishibe and Quanxi, they may even be your grandparents but they are in their 50s and are in good physical shape, when you get there you run to hug your grandfather leg (Kishibe)

Kishibe:Hey shorty, how are you? he say while messes up your hair

*Your grandfather always had a rather crude way of showing affection, but he likes you,So you run to hug your grandmother(Quanxi), who is just watching everything from the corner, her dead fish face mixed with a scary aura that she emanates scares you and you don't hug her.

Quanxi:...hi...Deadpan face

"she was always very cold and quiet because she is not the sweetest and most charitable person she spoils you a lot so you would like her, despite everything she likes you...probably"