|“||I want to find methods that work for everyone and then mass-produce Perfect All-Rounders. My long-term goals are different from Kō's.||”|
Arafune is a light-skinned, lean young adult with messy, medium-length brown hair. He is usually wearing a black cap. He is seen wearing a buttoned shirts and leaving the top button undone. At Border's HQ he wears casual clothes, such as a skin-tight black shirt and a light-colored sweater he keeps tied around his waist.
In his trion body, he wears his squad uniform with a turquoise and black cap. He typically wears his uniform jacket zipped all the way up. He is also seen in a flashback wearing a brown long sleeve t-shirt with a Border Logo on the sleeve, along with a black cap, another trion body outfit.
Arafune may come initially across as rude due to his habit of not mincing words and his manner of speaking occasionally being coarse, but he is considered a nice guy by other Border agents, and he was seen speaking harshly only to or about his friends and people who would not get upset. He has a somewhat sarcastic sense of humor. He is fairly sociable, on friendly terms with a good number of Border agents, and he doesn't shy away from offering advice. 
Although he enjoys competition and combat and can be observed smiling before and during rank battles he does not resent agents who best him. When the stakes are real, such as during Neighbor attacks, he is serious, focused and keeps his speech neutral and to the point. He is very self-confident and ambitious, his aspiration being not only to become the first Perfect All-Rounder since Reiji Kizaki, but also to develop theories based on his experiences to mass-produce Perfect All-Rounders. He proved the plausibility of this, however, when he used his theory to mentor Kō Murakami, teaching him kogetsu and attacker strategies. His attacker theory was so successful that Murakami, with the help of his Side Effect, beat Arafune in points within 8 months.
- (To Tamakoma Second) "Amateurs! You gave yourselves away!"
- (To various people) "I'll cut you down to size."
- (To Kuruma) "I want to find methods that work for everyone and then mass-produce Perfect All-Rounders. My long-term goals are different from Kō's."
- (To Murakami) "Hey Kō, sounds to me like you're drunk on your own power. You think just because you beat me, now you're king of the world? You're 'stealing everyone's hard work'? My teaching skills are just that good! Don't be so full of yourself! That crap should be saved until after you beat Tachikawa, Kazama and Kage! All right?"
- "They don't bite, do they? I don't like dogs..."
- (To Ema) "If you're so worried about her then go protect her yourself!"
- Arafune likes okonomiyaki (a type of Japanese pancake), chilled tofu salad, action movies, and tea and dislikes dogs.
- The reason behind his fear of dogs is that he was bitten by a small dog on his right butt cheek for no reason when he was young, leaving a scar that still remains even now.
- He is unable to swim, to the point where he is reluctant to submerge his face.
- He goes to the prep school and is one of the few B-rank agents with good grades.
- Arafune is considering getting a motorbike license.
- He erroneously assumed that Yūma had been taught by Kizaki and Yūichi Jin, when in fact his only mentor in Border was Kirie Konami.
- In the magazine release of Chapter 87, Arafune's uniform is erroneously drawn with the white stripes colored in. This was later fixed in the volume release.
- The author joked that since he often draws Arafune jumping off buildings, the Sniper chooses them precisely so that he can leap off later.
- His voice actor, Eiji Takemoto, also voices Katsumi Karasawa.
- World Trigger Manga — Chapter 95 (p. 4)
- World Trigger Manga — Chapter 87 (p. 12)
- Daisuke Ashihara: Q75: Arafune’s name is "Tetsuji", does he have an older brother? A: He doesn’t. It’s because his father’s name is "Tetsuya".
Source: Border Briefing File, Question 75
- World Trigger Manga — Chapter 89 (p. 18)
- World Trigger Manga — Chapter 92 (p. 17)
- World Trigger Manga — Chapter 163 (p. 17)
- World Trigger Manga — Chapter 95 (p. 5)
- World Trigger Manga — Chapter 89 (p. 19)
- World Trigger Manga — Chapter 95 (p. 3)
- World Trigger Manga — [[ | Chapter 163p19]] Cite error: Invalid
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- World Trigger Manga — Chapter 88 (p. 7)
- World Trigger Manga — Chapter 90 (p. 2)
- World Trigger Manga — Chapter 95 (p. 4-5)
- World Trigger Manga — Chapter 54
- World Trigger Manga — Chapter 58
- World Trigger Manga — Chapter 59
- World Trigger Manga — Chapter 60
- World Trigger Manga — Chapter 129
- World Trigger Manga — Chapter 136
- World Trigger Manga — Chapter 88 (p. 14)
- World Trigger Manga — Chapter 92 (p. 18)
- World Trigger Manga — Chapter 124 (p. 17)
- World Trigger Manga — Border Briefing File (p. 166)
- Volume 8 Character Profiles
- Daisuke Ashihara: Q79: What is the reason behind Tetsuji Arafune disliking dogs? A: Because he was bitten by a small dog on his right butt cheek for no reason when he was young. The scar still remains even now.
Source: Border Briefing File, Question 79
- Daisuke Ashihara: Q77: Arafune’s weakness had "can’t swim", but what is his limit? A: At the point of putting his face in the water, he is breaking through his limits.
Source: Border Briefing File, Question 77
- Daisuke Ashihara: Q: Is there anyone of 18 and above who has a driver’s license for a car or a bike? A: Aside from Reiji who has already driven in the story, it seems Fuyushima, Azuma, Suwa, Tsutsumi, Kako, and Kakizaki have normal driver’s licenses. The top brass and Sawamura have licenses too. Tachikawa doesn’t as you might expect. Zoe has a motorbike license, and Kage and Tōma have motorized bicycle licenses. It seems Arafune and Hokari want motorbike licenses too.
Source: Question Corner 15, Volume 20
- World Trigger Manga — Chapter 90 (p. 9)
- World Trigger Manga — Chapter 87 (p. 14)