Kouta gets cockier every time he goes Kachidoki, even if he was depressed before its usage.
Micchy decided he was the hero because he had enough information to use other like pawns.
Kaito was a little bitch with a heart before and now is just a little bitch.
Hase became a literal monster.
The only thing stopping Jonouchi from becoming more like them is the adult guidance of Oren and the responsibilities the latter imposes on him.
Likewise, up until this episode Zack had the city to protect but not the power or knowledge the others have, and managed to stay completely stable. From now on, things might change due to the Yggdrasil information being shared around.
Meanwhile, all their friends not involved in the fight remained the same persons; that's because they are civilians while the main characters are soldiers.