He is a portly man around his midle age. He is bald with brown side burns and a long eccentric mustache. He is almost always seen in his work outfit, consisting of a green vest and white shirt underneath with a black bowtie. He wears black pants and black shoes to complete the outfit.
Tetsu is a very kind, agreeable, patient person. He is friendly and usually shown with a smile. He cares for those close to him and is always willing to repay a debt he owes to his friends or family. He will also protect them, as shown when he protected Black Jack from getting arrested by Detective Takasugi by stealing his warrant to arrest Black Jack.
Tetsu worked as a magician in a bar but business became bad soon after as customers became less interested in his show. To attract even more costumers, he invented a new magic trick that is secretly getting a card out from his jacket's inner pocket. One day, during his performance, he collapsed due to tiredness and was fired soon after. At the train station, he accidentally bumped onto a random person and pickpocket him. Finding this as a new way to earn money, Tetsu starts to pickpocket people naturally by using his new magic trick. Later on, he was followed by a cop but the cop failed to arrest him as Tetsu always finds a way to escape.
One day, he pickpocket a pickpocket. The pickpocket and his partner chased Tetsu with the cop on their heels. Tetsu ran until he stepped into a heavy traffic, causing a lorry carrying some long glass panes to skid and one of the glass fell from the back of the lorry, cutting both Tetsu's fingers off. The cop begged Black Jack to cure Tetsu so that he could continue his pickpocket habit and easily arrest him. Black jack proceeds with the surgery and Tetsu's fingers are reattached once again. After rehabilitation, Tetsu and Black Jack tricked the cop by pretending that Tetsu's fingers couldn't work anymore. Disappointed, the cop left. Tetsu thanked Black Jack for helping him and proceeds to start a new life by working as a barista in Tom's Coffee Shop.
Black Jack usually frequents his cafe Tom's Coffee Shop and enjoys the coffee there. Black Jack, along with the majority of the recurring cast, frequent or are shown hanging out at the cafe, and there are times when certain requests come in from this shop. Tetsu himself never has a major role in any episodes except episode 20 that explained his past and is usually a side character meant to add commentary to the events going on.
As a former magician, he can perform simple magic tricks. He was also a former pickpocket and can still move his fingers as swiftly as he did in the past, able to secretly steal Detective Takasugi's warrant to arrest Black Jack without him noticing.
- Black Jack: After Black Jack sewed his fingers back on and lied to Detective Takasugi about how Tetsu could no longer pickpocket as his fingers no longer worked in good condition, Tetsu has been grateful to him since and values him as a friend and a customer. Once, when Kumiko needed surgery, Black Jack requested a month of free coffee and Pinoko specials (those were for Pinoko only) because he loved the coffee Tetsu made. Black Jack was also thankful when Tetsu stole Detective Takasugi's warrant to arrest him.
- Kumiko: His adopted daughter who he cares for very much. She works at Tom's Coffee Shop alongside Tetsu and the two love each other like family.
- Joutarou Honma: He is the doctor who warned Tetsu about his condition and treated him but told him to stop being a magician as the stress of being on stage would cause a relapse of his illness due to the amount of stress and pressure. He is grateful for Honma's treatment and as such took his daughter when he died and treats her like his own daughter.
- Pinoko: Pinoko loves the parfaits Tetsu made and Tetsu named them Pinoko special after her. He seems to treat her like a second daughter.
- Sharaku: He likes Sharaku as a son and lets him hang out at his coffee shop often.
- Chiyoko: He does not interact with Chiyoko much but the two seem to get along well.
- He was also treated by Dr. Honma Jotaro in the past. After Honma passed away, Tetsu took in Kumiko and raised her up as his own daughter to thank him.
- He lost a few of his fingers in a truck accident where the glass the truck was carrying broke onto the ground and cut his fingers off in the process. Detective Takasugi requested Black Jack to fix his fingers in order for the detective to once again begin chasing Tetsu and expose his crimes but Black Jack got back at the detective by lying and saying his fingers were no longer working properly. It is still possible to see the stitches on his fingers.