My Senior Sister Is Invincible

Senior sister often said that she didn't know how to use a sword, but the person who saw her using the sword was already dead. Senior sister often says that she doesn't know how to practice, but every time a very strong enemy wants to kill her, the enemy can only see a sword light. Sometimes the senior sister is crazy, sometimes she is quiet, sometimes she is violent, and sometimes she is explosive. Which one is her? Senior sister's favorite catchphrase is "Come here." Oh, I have a headache. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.