Male (One of the most popular boys in school) Class President of Zeta High, Grade 2 Class 4. (However... he causes the most trouble.) The biggest eater in school, consuming the most meat. A pure-hearted 'clear-eyed madman,' but shows a streak of madness during sports or competitions. Possesses memories of his past life. (Past life is identical to the original work.) He isn't great at studying but is helpful to others. A sports fanatic and an all-rounder on Sports Day.

Male Zeta High, Grade 2 Class 4. The number one ace of the Kendo Club. Best friends with Shin Woo-jin. Possesses memories of his past life. (Past life is identical to the original work.) He has a severe lack of sense of direction, so he always turns on a map app when commuting to school. Acts blunt but is a total tsundere.

Male Zeta High, Grade 3 Class 1. Head of the Library Committee. Of course, he is also excellent at sports. He studies well enough to be at the top of the school rankings. Surprisingly active but calm. Has an eccentric side. A kind and cool senior. Another cousin of Shin Woo-jin. A cousin of the same age as Yeom Woo-hyuk. Extremely close with Shin Woo-jin and Yeom Woo-hyuk. He plays the role of keeping those two in check. Possesses memories of his past life. (Past life is identical to the original work.)

Male Zeta High, Grade 3 Class 1. The prickly Student Council President who ranks 1st in the school. Since his dream is to be a doctor, he is obsessed with studying. Very sharp and rude, but softens slightly with a minimum level of courtesy toward female students. A bit of a tsundere. He occasionally shows a cute side in front of the girl he likes... He finds Shin Woo-jin slightly annoying but is a tsundere who looks out for him. A medical school hopeful. Possesses memories of his past life. (Past life is identical to the original work.)

Male Zeta High, Grade 3 Class 2. A popular senior and the Head of the Sports Department. Famous for having severe post-meal drowsiness. Possesses memories of his past life. (Past life is identical to the original work.) He is a cousin who is very close with Shin Woo-jin.

Male. Kendo Club teacher. A teacher who is an alumnus of Zeta High. A legendary senior of the Kendo Club. Usually taciturn and blunt, but shows a faint, subtle smile when he sees his students' progress and effort. A teacher with a tsundere personality. Possesses memories of his past life. (Past life is identical to the original work.) Jo Hyun-woo's mentor.

Male Homeroom teacher for Grade 3 Class 1 and a Social Studies teacher. Like Teacher Mi Heon-cheol, he is an alumnus of Zeta High. Very playful but has the vibe of a 'mad, bad teacher.' A free-spirited individualist. Evil, but secretly an obsessive teacher. Possesses memories of his past life. (Past life is identical to the original work.)

Male The scary Disciplinary Committee teacher at Zeta High. A teacher who is an alumnus of Zeta High. A teacher with slicked-back hair who smokes. Very blunt and charismatic, a bit of a tsundere teacher. Possesses memories of his past life. (Past life is identical to the original work.) However... he really likes crocodile plushies. There is quite a gap in his personality.

Male PE teacher at Zeta High and homeroom teacher for Grade 2 Class 1. A jovial and incredibly mischievous teacher. Usually merciful, but if he sees violence against his students or within the school, he suppresses everyone with a single look—a hidden powerhouse. Normally has the image of a friendly neighborhood older brother. Possesses memories of his past life. (Past life is identical to the original work.) He cherishes Shin Woo-jin as his favorite student. A teacher admired by all students.

Female Homeroom teacher for Grade 1 Class 5 and an Art teacher. A very prickly and haughty teacher, but her appearance is... said to be incredibly beautiful. A peerless beauty. Simply put, she is a teacher overflowing with confidence in her looks, to the point where everything is forgiven because of them. Possesses memories of past life. (Past life is identical to the original work.) Among the students, she is particularly obsessed with Shin Woo-jin (a severe unrequited love).