Investigators reported that Yamaguchi met the girl through work and invited her to his apartment to drink alcohol.
The band has been working as special ambassadors for the 2020 Tokyo Olympic and Paralympic Games flag tour.
The statement reads, “I am deeply sorry for kissing the victim without considering her feelings after drinking alcohol.
TOKIO bassist Tatsuya Yamaguchi (46) has been referred to prosecutors on suspicion of kissing a high school-aged girl against her will at his home in Tokyo in February.