Kuya's skinny because of his programming making him so poor, he can't afford enough food to keep his weight up but if he managed to get some more food on a regular basis he'd actually be pretty muscular
Kyoko's may not like Akina but she really wants to, she just feels like Akina is pushed too hard by some of her programming and a lot of her bad choices and tries really hard to get past it
Akina actually is under a lot of stress from programmed memories of what her family would be like as well as her expectations for the plot of the game which is a big reason why she's so irritable and placed herself so much higher than others
Kuya's a masochist there is nothing he loves more than being hurt during sex but he's also big on kissing so if he can he will
Kyoko's actually pretty big on swallowing and blindfolds, she also looooves to have her hair touched during
Akina's surprisingly submissive and will basically do almost anything she's told to do, she'll always sass back but she'll do it
Kuya's a goofy drunk and likes to pester people while drunk
Kyoko prefers to not drink but when she does she's very sleepy
Akina is not much different but some of her filters kind of vaporize
Kuya sleeps like a rock it's really hard to get him up before he's ready
Kyoko rolls around a lot when she sleeps, it's really hard for someone to sleep next to her because she tends to push people off the bed accidentally
Akina doesn't move at all when she sleeps and she basically turns into dead weight so it's hard to move her)