The 19-year-old leapt 99.5m on her second jump on the Lahti hill to win with a total of 251.3 pts ahead of Slovenia's Maja Vtic (238.7pts) and Japan's Yuki Ito (232.2).
It means Takanashi now has an insurmountable lead of 431 points ahead of her nearest rival, Austria's Daniela Iraschko-Stolz, with only four events left of the season which would bring a maximum total of 400pts.