KOuki and RItzu thing cause Fops convinced me sorry they're really bad
Kouki Stands at "6'4 while Ritzu stands at "5'1, Kouki is 18 while Ritzu is 14.
What isn't shown in that picture is that Kouki's eyes are purple.
When Kouki and Ritzu were 8 and 4 respectively, Ritzu ended up giving one of her purple bows to Kouki, he's kept it ever since(you can see it on the picture), while Ritzu loves playing detective and getting into trouble, Kouki is a protective big brother and makes sure to follow her around so she doesn't get hurt(even though he's not to big on the detective thing, if anything, he doesn't like the looks of corpses.).
With Kyouko, Ritzu and Kouki have a respectful and polite relationship, while with Makoto it's more playful(The boys have made it somewhat of a tradition to play fight now and then, the loser gets nuggied.). Ritzu calls Kyouko and Makoto "Mum and Dad" while Kouki calls them "Ma and Fa".
Due to Ritzu wanting to be a detective, she craves her mothers attention and praise, when Kyouko does give her some kind of affection, Ritzu acts like it was the best thing to ever happen in her life.
Ritzu has a thing of hiding behind Kouki when she's scared, considering he's quite tall.
The two are never normally without each other.
Ritzu's curvy ahoge interacts with her emotions, becoming wobbly and droopy when she's sad, becomes spikey when she's mad, wiggles when she's happy etc. Kouki's does not do this.
When they yell the Naegi catchphrase ("You've got that wrong!") they say it in such sync they have to take a minute to process what just went on.
Kouki doesn't cry in front of Ritzu, instead he would find Makoto and just bury his head of his shoulder and just cry.