The Babypips table is based on an 8am-5pm business day in each market. So.....
• 8am-5pm in Tokyo is 11pm-8am GMT, summer and winter
• 8am-5pm in London is 7am-4pm GMT in the summer, and 8am-5pm GMT in the winter
• 8am-5pm in New York is 12pm-9pm GMT in the summer, and 1pm-10pm GMT in the winter
In the Nial Fuller webpage which you referenced, he uses 8am-5pm local time for market hours in London, and in New York. But, for whatever reason, he uses 9am-6pm local time for market hours in Tokyo.
If you prefer Nial Fuller's 9am-6pm JST market hours for Tokyo, then use those hours.
Trading session times are merely indications of peak volume times. Trading does not abruptly begin at the designated "opening" time, and then abruptly end at the designated "closing" time.
In every forex market, there is light-volume trading in the overnight period. Then, volume rises dramatically in the early morning, fluctuates somewhat throughout the day, and falls off ripidly in the late afternoon.
The high volume period each day, in each market, basically coincides with the normal business day in that market. But, there is no "opening bell" to signal the exact moment when the trading session begins; and there is no "closing bell" to signal the exact moment when the trading session ends.
So, if you don't like an 8am-5pm business day (and forex trading day) for Japan, then use the hours that you do like.