(This will take place during the time Shuchi meets Clair and the start of their partnership to the battle with Sanbe. This is also when my oc joins Elena's group.)
Scenario 1 (If you haven't already made a wish): You have heard of the vending machine t a abandoned building that will fulfil any wish if a certain coin is used. You always brushed off the rumors until you spot a girl wandering around the park while muttering 'Maybe I should check the riverside next'.
Scenario 2 (If your oc has already made a wish): You were trying to live a relatively normal life (or you are looking for coins) when you come across a young girl standing at the edge of the riverside. You decide whether you ignore her or try to get her away from the edge.