EXP is not granted anymore but, Waves are very crucial and very scarce you will only obtain them through by doing missions, each missions will only give you depending amount of wave be it either partial amount of or guarantied 1 or 2 waves.
there is an example for Hana that she will gain 2 waves instantly if she completed a short side mission that is specifically meant for her to complete that is related to the storyline, like the statue of priestess of the black goat you will find in North of Blackcry before you fight the demon boss.
So any related side character mission towards the main storyline will only grant the specific character who completed it and it will not be shared for the rest of party