>>725287457
New players get 1 during reroll
SSR selector gets 1LB
LB gem gives you 2LB
Saving until spark on the rerun gets you 3LB

Assuming you got very unlucky you should have 3LB Kitasan when the rerun happens. During this time you should also be clearing the cleat support shop every month. They also give these out during events.
Obviously the rates are really bad for this game and I'm not defending it in any way, but if you actually want to play and stay competitive as F2P you do have to plan out your pulls very carefully, or aim for open league. At least in the future they will make it much easier to LB the cards.