I would like to iniciate by saying kudos for the the game so far.
Now for some idieas, what about existing raid bosses where the player would attack without its harem the raid boss and so accumulate partiipation points till the boss were taken down it could be an guild or world event where many people could participate in.
More having a lot of girls of the same character in a harem is like a bit crazy its like having a cloning factory in your house why not everytime y get an new appearce you can change the name of the character to right or left and so access the new unlocked apearences yet you would have to pay the money and invest aff to unlock the apearences still. That way it wouldn't clutter that much and by so be more organized. It's not the quantity but the quality. ^^
As for the pvp now in the game, why not make it different and by making the opponent challenge your harem chossen girls and you the opponents that way it will be an double see see how your strenght fars well against their girls and your girls against the opponent so it takes double effort the win a match and so make a reason to make the girls stronger and use more tactic in that domain.
Itemization for girls like the hero, gaining an new shop tab also to acess it.
New realms themes -> Sailor moon, Dragon ball, Pokémon, Avatar etc. . Also probably more furry related ones adn by soe a realm for them aswell, dunno.