The Hoops confirmed they had reached agreement with Vissel Kobe to sign Japan international forward Kyogo Furuhashi on a four-year contract.
The 26-year-old scored 14 goals in 20 matches of the ongoing J1 League campaign.
He is well known to manager Ange Postecoglou, who recently arrived from Yokohama Marinos, and becomes Celtic's second capture of the week following the arrival of Israel international Liel Abada from Maccabi Petah Tikva.
Postecoglou told Celtic's official website: "We are delighted to bring Kyogo Furuhashi to Celtic. He is a player of real quality and clearly someone I know well.
"I think he will add something special to our squad and I am sure the way he plays will excite our supporters. We look forward to welcoming him to Celtic."
Furuhashi, who has scored three times in six internationals, helped Vissel Kobe win the only two trophies in their history.
He was part of the side that lifted the Emperor's Cup on New Year's Day in 2020 and subsequently beat Postecoglou's Yokohama side in the Japanese Super Cup.
It is unclear whether Furuhashi will arrive in time to feature in Celtic's opening Champions League qualifier against Midtjylland, the first leg of which takes place at Parkhead on Tuesday.
Abada took part in his first training session on Friday morning and immediately felt at home.
The 19-year-old right-winger, who can also play up front, made his full international debut last month and jumped at the chance to sign for Celtic.
The teenager, who recently saw a move to Dynamo Kiev fall through, said: "It's amazing for me to come to a big club like Celtic. I really want to show the supporters and the club what I can do.
"It was last week that I received information that the club were interested in me. I didn't think twice. I immediately said 'yes' and I arrived a week later.
"It's a really exciting prospect to play in front a full stadium and I can't wait for this."
Abada is the latest in a long line of Israelis to sign for Celtic and joins current international team-mate Nir Bitton in Glasgow.
"It always helps when you have someone that can help you settle in and I believe it will help me integrate with the rest of the squad," he said through an interpreter.
"All the players received me very well at the first session and it almost feels like I'm at home."
Celtic take on Preston at Parkhead on Saturday in a friendly.