The striker will join up with her new Albion teammates when she returns from the Olympics in Paris, ahead of the new Barclays Women’s Super League season.
Managing director of women’s and girls’ football Zoe Johnson said, “We’re delighted to welcome Kiko to the club. She comes to us with a lot of experience at the highest level in Japan, which has earned her a well-deserved place in the Olympic squad this upcoming tournament.
“We look forward to working with Kiko and seeing her career develop in the WSL.”
The 27-year-old joins us after a 15-year spell with Urawa Reds, where she made more than 150 appearances.
Kiko has made 21 appearances for Japan since her debut in 2019, including three last season and will be a part of Japan’s squad for the Olympics in Paris in July and August.