Reports linking the Premier League leaders with the 22-year-old first surfaced earlier this week, with newspaper Sports Nippon claiming that the Blues spotted him last May and made an official approach in March.
Jose Mourinho's men are said to have offered around £4 million for the Japan international, though Tokyo chief Naoki Ogane stopped short of confirming the exact figures involved.
"It is true that Chelsea sent us an offer for Muto," Ogane confirmed to Sports Nippon. "It is a formal offer with conditions. They want to acquire him in the summer"
Muto himself, however, says he has not yet made up his mind whether he will make the move to Stamford Bridge.
"I have not decided yet at all," he added. "It is an honour for me to receive this offer from a great club."
Muto has not played 75 per cent of his country's matches in the past two years and would therefore struggle to obtain a work permit at the first time of asking, though Ogane insists there will be "no problems" on that front.
He also stated that Chelsea's approach for Muto is not connected to the club's new shirt sponsorship deal with Yokohama Rubber, which was announced in February.