If I have one extra day in my current plan, which city should I extend?

This is my current itinerary for late September. I am arriving at Tokyo on a Friday 4PM, and will visit Kawaguchi, FujiQ, DisneySea, Kanazawa, Takayama within the following 9 day. It's a little rushed so am considering extending one day.

• I can either spend one more day in one of the following cities, or visit a new city. Were would you recommend?
• Also, on my day 9, was thinking if I should go from Takayama to Tokyo instead, and fly back from Tokyo at 6PM on Sunday. This will give me a few extra hours to explore Tokyo on the last day. But the train from Takayama to Tokyo will be longer (hence a more tiring Saturday)

Day 1 Fri: Friday Arriving Tokyo at 4PM

Day 2 Sat: Tokyo > Lake Kawaguchi

Day 3 Sun: Lake kawaguchi (FujiQ)

Day 4 Mon: Lake kawaguchi > Tokyo

Day 5 Tue: Tokyo (Disney SEA)

Day 6 Wed: Tokyo > Kanazawa

Day 7 Thu: Kanazawa

Day 8 Fri: Kanazawa > Takayama

Day 9 Sat: Takayama > Nagoya

Day 10 Sun: Nagoya > Singapore Flight depart at 10:30AM