The 19-year-old from Gwangju, South Korea took just over 30 minutes to end PV Sindhu's hopes of a second year-end title with a 21-16, 21-12 win.
PV Sindhu, the reigning world champion, had to work hard to beat Yujin 14-21, 21-19, 21-14 in an hour and six minutes in the quarterfinal.
Indian badminton great Prakash Padukone will receive the prestigious Lifetime Achievement Award this year from the Badminton World Federation (BWF).
The 26-year-old from Hyderabad squandered a one-game advantage to lose 21-18 16-21 12-21 against the world number 43 Takahashi.
Sindhu looked sluggish in her first event in two months at last week's Denmark Open, where she lost in the quarterfinals to fast-rising Korean An Seyoung.
Sindhu, a bronze medalist at the Tokyo Olympics, took a break due to the hectic schedule during the Games, but she will be eager to win.
PV Sindhu has not been included as she had requested not to be considered for selection citing post Tokyo Olympics recovery.
The BWF confirmed that the Super 750 tournament will not be rescheduled within the Olympic qualification window.
This decision has been taken in the wake of a sudden rise in the COVID-19 cases in New Delhi, and an announcement of the lockdown in the city.
The Russian Open and the Indonesia Masters Super 100 were scheduled for July and October respectively but were derailed by the pandemic.