What day of the week and what time do you have many players on the multiplayer server?(I would be grateful if you could answer in Japan time, but it is okay in US time)
From what I've looked at, literally any hour at least one person is on, it doesn't matter what server (unless its password protected), normally I see the most people at 1-6 AM Japan Time. However its different for what day you play.
It should be noted at around 12:00 PM at British Time (and all other European Times) practically nobody is online. This is because most people are asleep at this time. Because of this, i don't see too many players online :/