Hearts are considered the secondary in-game currency in Mystic Messenger.
Throughout the game, the player can collect hearts by participating in the chatrooms, messages, some visual novels, and 707's spaceship. Hearts can come in six different colours, with five of each color symbolizing a different character. Depending on the player's choices, they will get hearts of different colours. Hearts are necessary for making important progress in-game, with regard to obtaining routes and specific endings.
See also: Endings
GameplayIf you give an answer in a chat or a text message, hearts in different colors will fly out, which goes off as a sign that the player has given an answer in favour of a certain character. It is important to note the colour of the hearts because it determines which route you will get during the first four days of gameplay.
White hearts on the other hand, are bugs according to Cheritz.
In Casual Story, the player should collect either yellow, grey or green hearts in order to make important progress - especially in the first four days of gameplay as this would determine the route the player will obtain at the game branch on Day 4. The player may collect red or purple hearts as well, but too many will change the game progress and may result as Casual Story Bad Ending instead.
In Deep Story the player should collect either red or purple hearts in order to make important progress - especially in the first four days of gameplay as this would determine the route the player will obtain at the game branch on Day 4. The player may collect yellow, green or grey hearts as well, but too many will change the game progress and may result Deep Story Bad Ending instead.
The player can choose to trade 100 hearts for one hourglass.
During a chat, if the player chooses answers that goes against the values of certain characters, they may get a broken heart. It comes in the form of a giant black broken heart which would have the colour of the offended character's heart at the tip. Obtaining a broken heart would cause the player to lose one heart from their total heart count. Should the player earn no hearts in the chatroom, they will get a -1 heart count for that chat event. You can also get broken hearts in messages depending on the options you'll choose.
Once the UFO reaches the Honey Buddha Chips bag, you can open the bag by tapping it and get 0-100 hearts depending on the quote you get. It takes roughly 4 hours for the bar to fill up completely.