You can improve your relationship with the characters by meeting up with them. You can meet up with a character every 6 hours. Play the mini-game and gather as many points as possible to obtain rewards!
 
How to play the mini-game?
The goal of the mini-game is to collect as many objects on the field as possible. The more objects you collect, the better the rewards will be (energy, experience points, relationship points).

Connect at least 2 objects of the same color on the field with a straight line. If you manage to connect objects into a square figure, it will remove all the objects of that particular color from the field and give you some extra points. Make sure to connect the line to close the square figure all the way to the end for it to work.
Every object removed from the field will bring you 10 points.
 
 

NOTE: Normally, you have 15 moves total every time you play the mini-game. There is an option to increase the number of moves by activating the Golden Ticket. More information is available under the link.