Level up by releasing the level cap 5000 ... However, with existing training items, it is difficult to use only "grilled fish", "silver bells", and "golden bells" to raise the level of 3000 or more characters by training.
Even if you try to raise the level with bonus battle super EXP, it is painful 25 times.
So, I was interested in the training item "Pizza".It seems that you can exchange 300 Kizuna coins and 10 pizzas at the Kizuna coin exchange.
You can exchange it at the Co-op exchange.