This will explain what the traits do in game.
Other Koikatsu Party Guides:
Quirks and What They Do
Many of these quirks effects was found: playing around in game, confirm by other on the Japaneses version wiki, and other players. For the most part everything is straight forward.
She will go to the bathroom more often.
Often performs related eating animation (So expect to see her somewhere eating).
Doesn't get upset if you grope during conversation but her affection will raise at a slower rate.
Does not get upset if they see you in restricted areas (bathrooms, locker rooms, etc). More likely to masturbate in open areas.
Increases affection rate when talking about lewd things and will follow the male characters into female restricted areas (bathrooms, locker room, etc).
Often performs reading animation (So expect to see her sitting down and reading somewhere).
Often performs animation of listening to music (Expect to see her listening to her headphones).
Will perform twice as many animations as other girls. (So where other girls do 1 or 2 animations before moving).
Increase rate they gain affection when asked questions by the player. Also increase the rates you gain experience on sex acts if the player assume a dominate role (I haven't confirmed but I believe this is fondling actions and insertion actions).
More likely to seek group and be around other girls. Increase affection rate.
Often performs animations of cleaning (Expect to see her wiping off desk, sweeping the floor, and etc).
Sex rates increases at a slower rates when performing sex acts that require the girl to take the iniative.
More likely to teleport around the map.
Stays around from the other girls. More likely to go an area of the map with the least amount of people.
More likely to perform animations of them exercising. (So expect to see them stretching or doing laps around the field).
Decrease the rate affection raises when discussing lewd things with them.
Will do lesbian acts with other girls with this trait.