Delinquents

The mysterious gang girls are future characters that are currently still in development.

Appearance
All of them have red-colored eyes and a variant of black hair styles. They all wear a short sleeved white seifuku with a long skirt and default shoes with white socks. They wear surgery masks with different symbols on it. This will not be the final appearance of these characters as they may change soon.

Member #1: This member has straight black hair with strands stick out from the sides. She wears a white mask with a large X on it.

Member #2: This member has straight long black hair. She wears a mask with sharp teeth on it (the same hairstyle of the student council president)

Member #3: This member has long black hair with a purple streak on her right side. Her hair covers her right eye and she wears a red mask with a female symbol on it. As she is the most unique, it is possible that she is the leader of this gang.

Member #4: This member has long black hair that reaches her thighs. She wears a white mask with a red Japanese symbol on it.

Member #5: This member has short hair similar to Rei Ayanami from the anime Neon Genesis Evangelion. She wears a blank white mask.

Trivia

 * YandereDev accidentally placed the screenshot of these characters on the "Photographs" folder in January 1st, 2016 Update. They were later removed in the January 2nd, 2016 Update.
 * These characters are still incomplete. YandereDev refuses to share any other information.
 * These girls might be a reference to Japanese female gang leaders called Sukeban (スケバン/女番/スケ番).