Research and Interrogation?

[Pixelabor]

Will it have any use in the future? so far it serves for nothing for me..... research only brings me cheat items when they complete 100% and some dudes i can make citizens(whats the purpose of this) and then Interrogatio i can make them my ally why would i do that? can i capture any rare enemy or something like it? the drink i get from interogation makes me strenght good but so far i dont need that.... what about chakra world how should i use it?

[Automaton Spy]

Research gets you the best weapons in the game if you keep at it.

Interrogation gets you extracts, that WILL make a difference later on.

Chara world ups your aptitudes, and teaches you useful abilities.

[Maya-Neko]

You can also strengthen your squads with interrogated prisoners. You obviously want to level up your interrogation squad first to the point, where you can interrogate alle prisoners at once.

[The Regal Machine]

Research: Gets you items and weapons some which are super rare and useful, prisoners that can be used to extract into an item which boosts stats, you can recruit them because later in the game you will be able to catch/imprison units that are not only levels higher than you but have mastery and skills mastered. It save you time from creating a unit from scratch and going the long way to making them strong. The citizen thing is for specific missions only. Once you clear those it's not need anymore. It also allows you to face boosted enemies with Overlord status.

Interrogation: makes it so you can do those things mentioned above but also boosts the exp the prisoner gives to your squad.
It's another layer of game play that makes your units stronger and more functional in battle.

Chara world: Also for boosting stats beyond their normal range and creating items that teach skills.

[ShinkuTear]

Research and Interrogation are the keys to getting into any sort of power. Chara World is(IMO) pretty fun, but the Aptitude boosts are fairly ignorable, equipment stats quickly become the lowest part of your stats until you are at the absolute end of postgame, and Aptitudes only affect equipment.