By ボスクリエーター 300 En no Otsukiai wiki page:
Manami Sugiura, a small girl contemplating which food to purchase with her restricted budget, is seen by a boy one day at the grocery. Due to her cuteness, the boy agrees to buy her a snack for 300 yen, but only in exchange for an unsuitable behavior.
The story starts in a local convenience store, where an 8 years old girl named Manami is having trouble deciding, what sweet stuff she should buy, while a boy is closely observing her since he finds her cute. She stops concentrating on her sweets, when she sees the boy is picking a chips bag without any trouble, which makes her envy. The boy, offers her to buy something for her which she gladly accepts, making …