Goro comes off as a polite, pleasant young man when you first meet him. When you get to meet him, he starts to show his true side; cocky, arrogant, and sarcastic. He acts very petty when it comes to his sister, Maki, because he's older than her, but she's taller than him. To compensate for that, he uses his knowledge against her. But it's not just Maki that feels the brunt of Goro's personality. He has found someone else to bother. Both he and Aru have the same ambitions for the future. Both  want to go into law enforcement as detectives. Aru is much more observant then Goro, so he likes to pull the "I'm taller and stronger then you, so, ha!" However, he is still capable of holding feelings of compassion towards others and is there for his friends when they need him.