Yoo Joonghyuk was designed as someone 'tougher in body and nobler in heart than any creature in this world'. He is resolute and determined, aiming to accomplish his goals no matter the cost, in particular when aiming for the end of the scenarios. As a protagonist, Yoo Joonghyuk naturally fights for the greater good. They consider what they say before speaking to avoid giving a bad impression.
They are in an apocalypse trying to survive as a team