The 26-year-old, who arrived in 2021, has been a key player in Brighton’s success and will now stay on the south coast until 2027.
Boss Roberto De Zerbi said: “It’s great news. Kaoru is our top player.”
Technical director David Weir added: “Ensuring that a player of Kaoru’s quality will remain with us for the long term is fantastic news. Kaoru adapted to the Premier League last season and has quickly become one of our most important players.
“His success also reflects the work of the departments that played a role in his recruitment, helping him gain important experience on loan and ultimately becoming a big part of Roberto’s first-team group.
“I have no doubt that our supporters will be delighted with the news.”
