Keitai Shoujo

The main character, Aida, is in the second year of high school.
It's almost Christmas, but I can't have a girlfriend again this year, so I feel a little nervous.
When I was surfing the Internet with my mobile phone to kill time, I found a site called "Gyaru ★ Mo~to" that I was a little curious about and downloaded the standby screen.When the download was over and the "completed" was displayed, the cell phone emitted the light I wanted, and there was a small girl giving it to me in the palm of my hand."I'm Lin. How about you?"
"If you can download me, isn't he there by any chance?" " I'm a little troubled if you can't be happy by Christmas.
I don't have time, so I'll explain..."
Saying that, Lin tells her that if Aida doesn't make her by Christmas, she won't be able to return to the original world.