Exclusive coin collected by the gravekeeper Lada.
A golden coin, with imprinted image of a flower.
You can obtain Belle Coin by defeating Arena Showdown or Champion Breaker and obtain it from Point Rewards during World Battle Tournament 18.
After the event, they are also available as loot from mob battles.
You can use Belle Coin to draw Belle Pact to get beautiful & mighty M and L familiars.