|“||[...] 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.||”|
Katsumi 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.
Karasawa is a recluse person who doesn't talk much, he usually just listens as others talk. From his point of view, he seems to like Neighbors and doesn't hate them. He even asked Osamu about why did Yūma come to their world, just so he could negotiate with him. He told Mr. Kinuta "[he] prefers to utilize rather than eliminate". He is shown to like heroism, taking a liking to Osamu due to his brave actions.
- (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..." 
- He likes cigarettes, rugby, pollock roe, and kamameshi (a dish with rice, meat, and vegetables in a small pot).
- He used to play rugby at University.
- His voice actor, Eiji Takemoto, also voices Tetsuji Arafune.