The Stonehearted Knight - Chapter 13: Crystal number three

The character with the highest difficulty and the worst performance, Baek Yuseol, was considered a trash character in-game because he could not use magic in a fantasy setting where everyone else could.However…[Because the wrong ending has been reached, 90% of Aether World has been destroyed.] [Please reach the “True Ending.”] Suddenly, those words echoed in my mind before I was transmigrated to the Aether World.[You can use the skill “Blink.”] “Just why did I possess this character?”Blink was the only magic skill I had.Surviving in Stella Academy among genius mages, I became the notorious Blink Mage.Alternative title: I Became A Flashing Genius At The Magic Academy

To reward Meng Fan for his bravery before his heroic death, the cosmos rewarded him with a ‘system’, sending him back in time to three months ago, alive.

- Description from Novelupdates

The story is about a man whose compulsive tendencies make it impossible for him to keep a job, and a young girl who skips school and loves insects. The two meet, come to support each other in reintegrating into society, and fall in love. There’s a problem, however: namely, the parasites in their heads.