Major spoiler for the main story:
Read at your own risk---
It's not that his arrogance is toned down. This is Clayman's original character. This is why Laplace in the canon questions Clayman's plans and behavior. As it turns out, Yuki has a skill that allows him to manipulate his target's thoughts and emotions. Yuki slowly amplified Clayman's arrogance, inferiority complex, and fear of being too weak to help his friends. Over the decades, Yuki carefully cultivated the worst version of Clayman to turn him into a puppet.
That's crazy!!! Makes me like Yuki even less now... Σ( ￣□￣||)
Make sense with how he was messing with Hinata (⊙…⊙ )
WAAHHHHHH I want him to be the main character so bad...Seriously what a great character development...If only this is canon then I will finally die happily, BUT it's not Anyways the art is good and with his arrogance and pride being toned down, his actions became suddenly cuute in my eyes....