Tetsuzō Satō is a participant in the Liar Game Tournament. He is notably ranked number one during the second round of the competition. Satō has a very distinctive appearance, characterized by his short hair and his choice of attire, which is a Mariners shirt bearing the number twenty-six. This clothing choice reflects his deep passion for baseball, a trait that is evident from the type of question he asks during the second round of the game.

Satō’s personality is initially unremarkable, as he blends in with the other waiting participants. However, his strong interest in baseball is a defining personal characteristic. Throughout the Revival Round, he displays a pragmatic and self-interested nature, primarily focused on his own financial gain and his desire to escape the Liar Game without debt. He is also shown to be capable of devising schemes, although these plans are not always successful.

In the story, Satō first appears in a large banquet hall where the second round is to be held. He participates in a practice round, where it is revealed he was part of the majority that lied about being a woman. When the actual game begins, he is the first participant selected to pose a question. His time in the second round is short-lived, as he loses on the first question, which forces him to proceed to the Revival Round. During the third question of the round, it is revealed that Satō and another player, Yuji Fukunaga, had formed their own group of eight people, similar to the strategy employed by the main character Shinichi Akiyama.

During the Revival Round, which takes place in a bowling alley, Satō’s baseball fandom comes to the forefront again when he reacts excitedly to seeing an L Ticket, which he recognizes as the same ballot used for a baseball player’s popularity contest. Initially, Satō is part of a collective alliance where all the players agree to make Fukunaga the loser. He shares his personal story and argues why he should be the one to win this round. His perspective on the player Nao Kanzaki changes dramatically when he learns that she is not in debt and has actually made a profit from the game; he becomes shocked and then distances himself from her. For the first eight voting rounds, Satō follows the group’s plan, consistently voting for a player named Takayoshi Miura and receiving votes from Kousuke Tsunoda.

In the ninth voting round, Satō agrees to a deal proposed by Nao Kanzaki, where she would give him seventy million yen in exchange for ten of his votes. He is later shocked to discover that Nao had made the same deal with every other player except Fukunaga. Unwilling to pay fifty million yen to Nao for votes, Satō devises a plan he believes is foolproof. His scheme involves selling his own votes at a high price and intentionally losing the round, which would remove him from the tournament while leaving him with substantial profits. He successfully sells some votes to Tsunoda for sixty-five million yen, but his attempts to sell votes to other players all fail. It is later revealed that his plan was exposed because Akiyama had informed all the other players about Satō’s intentions. With his plan in ruins, Satō has no choice but to purchase votes from Nao. By the time the tenth voting round’s results are announced, Satō is already aware that he will win. At the conclusion of the game, he joins the other players in celebrating Nao for enabling all of them to win.

Satō’s development shows a shift from a passive participant following an alliance to an active, if ultimately unsuccessful, schemer attempting to manipulate the game for maximum personal profit. His notable abilities include his capacity to form strategic alliances and his skill in vote trading, as demonstrated when he successfully sold votes for a high price to one player. However, his primary limitation is his inability to anticipate the counter-strategies of more perceptive players like Akiyama.