This guide will let you know how to unlock Sun Sword Style in Anime Fighting Simulator.
The first thing you will have to do is go to an NPC named Tanjiron. He will give you a quest to gain 500 increments of sword skill.
Complete this quest and move back to Tanjiron again. He will give you a new quest to kill 30 players with a sword style. You have to find some players and kill them with a sword style.
Head back to Tanjiron; he will ask you to complete another quest to defeat three masked villains. They are located in dimension 4.
Now Tanjiron will give you a quest to gain 1.75k increments of sword skill. Complete it, and then the last quest will be to defeat 75 players with a sword style.
Move back to Tanjiron, and he will tell you that you can get the sun sword style now. Go to Specials and unlock it. Try this out.