|“||[...] He was the one to make things come to this point. Despite all the risks, there are still people who value people like him. I am one of these people.||”|
Karasawa is a man with short hair slicked back. Being a high-ranking member of Border, he usually wears a suit, which has thin black stripes. During the Black Trigger Retrieval Arc, he wears a sweater over his suit, while away in the meeting. He is also often seen with a cigarette in his mouth, or an arched eyebrow when impressed. Rumor has it he used to play rugby.
Karasawa is a reclusive person who doesn't talk much, he usually just listens as others discuss. From his point of view, he seems to take an interest in Neighbors and doesn't hate them. He even asked Osamu why Yūma came to their world, just so he could negotiate with him. He once told Kinuta "[he] prefers to utilize rather than eliminate". He is shown to take notice of those who are able to stand up for what they deem right.
he seems to be quite physically fit, as he is shown assisting civilians by clearing rubble. He credits this to having played rugby as a student.
- (About negotiation) "If we know what they want, it's possible to negotiate with anyone. Even people from other worlds." 
- (About Osamu Mikumo) "[...] He was the one to make things come to this point. Despite all the risks, there are still people who value people like him. I am one of these people." 
- (To Yūichi Jin) "Jin... Don't be so down all the time. You need to support your apprentices. Hard days await for Osamu..." 
- "I am greedy by nature."
- He likes cigarettes, rugby, pollock roe, and kamameshi (a dish with rice, meat, and vegetables in a small iron pot).
- He used to play rugby at University.
- His voice actor, Eiji Takemoto, also voices Tetsuji Arafune.