Seibu Lions pitcher So Sou Sato (23) signed a professional contract at the team's office in Tokorozawa, Saitama Prefecture on the 30th and held a press conference. number will be 75. He expressed his enthusiasm, saying, "I want people to say that 75 for The Lions is Sato."

When I heard about the promotion to a controlling position, I said, "I honestly feel happy. When I thought about changing from three digits to two digits from here, I felt the weight of number though not nervousness," said Sou Sato. He reported the news to his family over the phone and beamed when his father told him, "I'm happy, but my dad is nervous too~.

Sou Sato was born in February 2003, but the "2002 generation" players like Watanabe, Hasegawa, and Yamamura have been more prominent. His teammate Sato Futoshi, who was drafted in the 2024 developmental draft, was promoted to the main roster during the 2025 season, so Sato So was left behind. "Until this year's rookies joined, I was the only one with a three-digit number. It was frustrating, and I watched them with the desire to make it to the first team too. Now that I'll be on the same stage, I'm determined to catch up and surpass them, and really stick with them," he said. He also mentioned that he reported it to Yamamura Takayoshi first, as he was the closest to him at the time, and that he congratulated him, saying, "You did it!!"

Sou Sato joined Seibu Lions in 2024 as the fourth pick in the developmental draft, after graduating from Sapporo Yamanote High School and Seisa Doto University. In his second year as a professional this season, he completed the first team's training camp in Nango, Miyazaki, but was sent down to the second team midway through the open season. In the farm team, he has made five appearances (four of which were starts), recording a stable record of 3 wins and 0 losses with ERA of 1.37.