My League is held from Monday to Sunday and ends at midnight on Sunday. (The in-game time is UTC-based.)
Want to be promoted to a higher league? You must win!

My League determines the rankings based on the amount of Gold that players have acquired during the week to determine whether a player is promoted, remaining, or demoted.
1 to 100 players are allowed in a single League Grade channel, and an additional reward is given if a player meets the requirements for a promotion reward for their League Grade.
Win 1vs1 Matches to accumulate a lot of Gold and wins during the week to reach the top of the rankings of your current League Grade.

When you finish at the top of the League Grade, you may be promoted to a higher Grade the following week.
If you do not play 1vs1 Matches during the week, however, your Grade will go down.