I like general faction system in this game, but only thing that I dislike is that some factions can't be joined by the player.

Old Guardians
This faction should have been joinable since most humanoid members of it act programmed or brainwashed, like awaiting commands or directives. It would make sense for the player to have the option to join this faction. For example, if the player has a mid or high reputation with the Old Guardians and is sent to the Processing level, they could acquire a "Hypnotised" or "Brainwashed" status modifier and faction outfit upon joining.

Angels
The Angels faction, despite featuring faction-specific restraints, functions more like a repless faction than a fully joinable faction. It should have been joinable in some conditions, having high rep with angels and low rep with demons and the blessing of light. Most members, like Orb of Light, use light-based abilities. 

Demons
Demons are listed as a faction in the journal but function as a repless faction with no actual members.

The general idea is that Demons could become a joinable faction under two conditions: having a negative reputation with both gods and most factions. Since gods typically assist with removing restraints and giving keys and provide valuable quest rewards, and a lot of factions offer friendly support that eases player movement and combat, joining the Demon faction would grant certain buffs and a special faction ability that gives players the ability to use demon-related abilities.

Cult of Bast
Currently a joinable faction, but the player’s role feels more like a partial member rather than a full member of the Cult of Bast. The faction is primarily composed of catgirls who, when attacked, have random dialogues about blessings. If unprovoked, their friendly dialogues often reference “becoming a catgirl”. This blessing may imply transforming into one of them, as they attempt to help the player by bonding them through restraint

Dressup Co
The faction is joinable but lacks most asylum- or hospital-related restraints despite having some variety. Their restraint options could be expanded.

do agree with this.

would make things also a little more interesting gameplay wise.

more options is alwayys a + for me,provided they are explained properly.

I want the NPCs in the game to remove some restrictions from me just like that, but not so that I would be free. Like all that NPCs can do now is constantly tie up, and layers of bondage are added and added randomly, if it is not a rope witch without things, for example. In general, there is not enough bondage style.