Alright let me clarify some things, so far since Hifumi has gotten the True System he has only had three unlocked at a time that can give him missions and rewards for completing objectives.
He can turn one off and activate another one but only after completing the mission set originally by the system can he deactivate that one and reactivate another one to take its place.
The ability to summon characters is available in all systems so long as you have the proper magic catalyst related to that summoning system like magic circuits for the FGO summons or the Summoners Pedestal from Grand Summoners and Brave Frontier and many other specific things needed to be allowed to summon characters from any gacha game out there.
So far he is only able to change out the Artist System and Health System as he still hasn't completed the original mission for the Romance System and can't change it out yet.
If he changes out a system he can't complete missions for the systems that aren't activated, however if he switches to a system that has a certain goal for him to accomplish it will automatically complete that mission if he had already completed that goal previously if it was a onetime goal to complete.
But if it's say like play on the guitar for an hour it won't count that, but if it was a mission for him to play at his first concert then when that system is activated it will be completed if that goal was already achieved.
So what I'm getting at is he's being rewarded for any and all major milestones he completes in his life it's only he gets the rewards when he activates a system to get the rewards for the things he has done.
So the next system I said before will be the Delivery System but I want suggestions for other systems he should activate that are in your guys mind interesting systems from their storys and how they would work in his world, but it has to be systems that aren't related to a certain race so like the Vampire System or Werewolf System or something like that won't be options for him to choose.
I'll probably upload another chapter later today or sometime really early tomorrow thanks to me having three day weekends from work for the next few weeks which is nice to have.
Also would anyone be interested in me officially opening up my Patr.eon? I have it there but I haven't officially worked on it or uploaded anything yet but it would let you guys have the option to ask what of my old works I should go back to if you have read any of them as that would be the only way I would find it in me to work on those stories all over again if people are genuinely interested.