He transmigrated into the world of Attack on Titan...

"Ding! Congratulations, you've picked up the Female Titan's power."

"Ding! Congratulations, you've picked up the Armored Titan's power."

"Ding! Congratulations, you've picked up the Colossal Titan's power."

Ji Yu feels that he might be the first man to possess the power of all Nine Titans since the Founding Titan.

(The synopsis isn't great, please just read the main text.)