This book that I've just finished is called Post-It by BelWatson on Wattpad.
I've been reading Bel's stories for about 2 years now and every single one is read withing two days or less because I'm always that hooked. She posts independent stories along with fanfiction stories (her one direction ones are my favorite). Post-It is one of the independent stories but the main guy in the story is based off of Harry Styles (which I didn't know until I had read the end note).
It's a very interesting story (which has a sequel that I can't wait to read)! One day, Maca finds a post-it note on a park bench and it brightened up her day so much that she decided to respond back to the note. This then leads to Maca befriending the person behind the post-it notes as they only talk through the post-its. After 5 months of talking via post-its, Maca agrees to meet this mysterious person behind the many smiles after reading these notes. But on the day of meeting this person, she finds a letter in place of the post it, and finds that she has to go on a scavenger hunt all around the city before she meets the mysterious person. The book is her adventures throughout the day.
The story was just so much fun to read as each chapter was full of wonder and happiness or uncovered part of a back-story behind either Maca or the mysterious guy, H.
Since there was no real conflict in the story, there is a need for a sequel, but you do see the ups and downs of Maca's experiences and you just want to find out who H is and what happens when they meet.
It was a very quick read and I could have finished it in a day, but due to school and staying up late, I had to make myself read it in 2 days. Definitely recommend this story!