Despite her old age, your grandma went off alone again to go to the supermarket.

As it sounds you go to the door to open it for your grandma. But it's not just your grandma standing at your door.

"Hey. My name is Mitsuya Takashi. I helped your grandma carry the shopping home." He smiles warmly at you and your grandma pushes past you into the house and mumbles to you:

"Today I'm your 'wing grandma'." She giggles and disappears into the kitchen, leaving you alone with the stranger.