When the snow and frozen sakura petals fall, a miko priestess would put on her bushi armor and perform a fiery dance with both blades drawn. While another Valkyrie brings divine mercy to redeem the faithful.
During Expansion Supplies, if you roll any combination of 100 rolls, be it singles or multis, you will be guaranteed to receive the featured S-rank valkyrie on your 100th roll if you did not receive it beforehand.
Each new expansion will reset your Expansion Supply count to 0.