cafe de plume

You, the protagonist (female), have moved to work in Kobe, where your grandmother used to live. Walking around Kobe for the first time in a long time, you find a small café with a nice atmosphere, run by a silver-haired young man. After ordering a cup of black tea, a past memory of your grandmother comes to your mind. After paying for the tea, you are about to leave the café, but for some reason cannot find your wallet. The shopkeeper then asks the protagonist to help him with something as an alternative to paying for the tea. What is this help? [Translated from Novelgame]