This page explains how to solve the quest "The Too-Visible Girl" in Yo-kai Watch.
Start the Quest
Go to the parking lot of the Everymart in Uptown Springdale to start the quest.
Yo-kai power...GO!
You need to have a Dimmy medal to complete the quest. Dimmy is a Rank E Yo-kai that can be found under vending machines and under cars in Uptown Springdale. His favorite food is rice balls, so buy some rice balls from Everymart and choose "Items" before tapping "Fight" when you battle Dimmy, then select a rice ball to throw it to Dimmy before you start the battle. This will slightly increase the chance that Dimmy will befriend you after the battle.
Quest Complete!
Once you have a Dimmy medal, talk to the celebrity so Dimmy can make her invisible.
Return to the List of Quests.