New Celtic forward Kyogo Furuhashi wrote "I'll never walk alone" and used the "NoToRacism" hashtag on his Instagram account on Monday after facing racist abuse by fans of Glasgow archrivals Rangers.
The video posted on social media showed Rangers fans traveling on a bus calling Furuhashi's name while singing a song insulting Asians, while one of them was also seen pulling his eyes closed.
Rangers released a statement that read, "The individuals involved have been identified and will be banned indefinitely from all Rangers games," with British media reporting local police are looking into the matter.
Furuhashi joined Celtic from J. League side Vissel Kobe over the summer and has quickly become a fan favorite after netting six goals in seven games.
New Celtic manager Ange Postecoglou expressed his feelings about the incident on the team's website.
"To be honest, it saddens me a lot because I'm the one who's brought him over," said Postecoglou, who left the J. League's Yokohama F. Marinos in June before signing Furuhashi to join him in Scotland.
"I know how polite and respectful the Japanese people were. ... I'm sure his experience is the extreme opposite of what's been portrayed in the last 48 hours."
"I've been talking to him and he loves being here, he loves the city, he loves the way everyone's embraced him. ... Our No. 1 priority is to protect and support the player."
Celtic will travel to face Rangers on Sunday in a Scottish Premiership match. The Old Firm derby is known as one of the fiercest rivalries in the world of sports.