Sword and Fairy: Together Forever

There are 12 opponents to beat scattered across the world, they are on the map with a green 3 card sign.

Once you have beaten these opponents and obtained their cards you must reach chapter 27 and the last 3 will appear in Mingshu Sect.

LOCATIONS

Mingshu Sect | Pingxi Village

Mingshu Sect | Swallow Valley

Tianshi Sect | Atrium of Tianshi Sect

Changbai Mountain | Changbai Mountain

Xianxia Sect | Mt. Emei Road

Flora Cliff | Deep in Flora Cliff

Lulong Town | Governor’s Mansion

Quanyin Village | Quanyin Village

Quanyin Village | Upper of Duzhang Spring

East Azure Abyss | East Azure Abyss Reef

Yanbo Spring | Yanbo Ancient Road

Heaven Demon Kingdom | Heaven Demon Palace

Mingshu Sect | Mingshu Sect – only after beating the first 12.
Mingshu Sect | Mingshu Sect – only after beating the first 12.
Mingshu Sect | Mingshu Sect – only after beating the first 12.

This is a guide explaining how to play the game since the tutorial is terrible at explaining it. It's actually a really fun game when you understand it.
Read FF Square Enix guide for the actual solution of finding the locations.

Concept

In short: It's rock, paper, scissors with a deck of 10 cards. Cards have colors and each color beats another:
Blue beats Green | Green beats Red | Red beats Blue.
The bottom left of your screen shows your color "mana" chart if you forget.

Cards

There are two types of cards:
1.) Basic ones that simply fill you a mana of that color (limit 1 mana stored per color).
2.) Action cards that spend your collected mana to either attack the opponent (red number) or heal yourself (green number). These action cards show their color costs on the bottom of them where you'll see, for example, a small blue and red circle meaning you need to have 1 blue and 1 red mana stored from basic cards first for it's action to play; otherwise it's just another basic card. They glow when ready and will cast their actions regardless of if you win or lose the play.

Gameplay

Each player plays a card at the same time and your goal is to guess which color the opponent is likely to play based on probabilities with their hand vs yours as well as mana either player is likely trying to get. When both cards are played, the winning color causes the onion thing to deal 1 damage to the opponent's health (leaves). It's game over when someone runs out of health. If nobody is dead after using all cards, the player with the most health wins.
If however you both play the same color, the damage instead gets stored in the onion thing and he grows bigger. Cards remain on board to show how much damage is stored. This can continue, technically the entire game if you are RNGesus but eventually someone will win a play, and at that point the onion thing will release all that damage onto the loser.

Conclusion

So now that you know how the game works, hope you find it fun strategizing probabilities! As you defeat opponents, you'll grow your card collection (menu->cards) and you can update it and edit it to your liking, which you should definitely do as there are some that are objectively better as you go.