The Japan international fired into the bottom corner from 16 yards out from Aleksandr Golovin’s cross.
The hosts had to finish with 10 men though when Thilo Kehrer was sent off for a professional foul on Ibrahim Mbaye after a video assistant referee review.
Monaco brought on Paul Pogba late on for his first home appearance for the club and only his second game in more than two years after a doping ban.
PSG pushed for an equaliser in injury time but Vitinha had a shot saved and Joao Neves missed with a header.
Monaco move up to sixth, while PSG could lose top spot to Marseille later.
Marseille, two points behind PSG, play Toulouse at 20:00 GMT.
