Main Character:

Asunaro Kohinata

Born Lucky: Played with. Zeyfur states that everyone goes through a lucky period in their life, but is surprised that he still has had an overall average life. However she later finds out that for some reason all of his luck is being saved up until after he is married. After that, he and his wife, will be granted a large amount of luck for the rest of their lives.
Character Development: For the course of the story he reevaluates his otaku life and decides to be better.
Decoy Protagonist: Reading Chapter 0 would give the impression that Asunaro is the main protagonist, but the next chapter introduces Serika, who fits this role better.
Locked Out of the Loop: Kohinata has absolutely no idea that all of the girls in his harem are in a Fate Worse than Death Deadly Game.
Minor Living Alone: Invoked by Zeyfur: she has his parent's jobs send them to some island so he can have the typical harem protagonist life.
Nice Guy: Though the girls were originally forced to be his harem members, his kind actions and willingness to help them causes them to gain actual feelings for him.

Zeyfur

Debt Detester: She is very fond of Asunaro's help, so she decides to make a Harem Death Game for a perfect wife for him as a compensation.
Exact Words: Very fond of this trope. Her deal with Kohinata was that she will make his fantasies come true and let him be with the girl he likes most. She leaves out the fact she is going to kill the girls who lose. She also adds this into the game rules, something Serika realizes.
Face of an Angel, Mind of a Demon: Zepfur looks like an adorable little demon girl, but she is very twisted and devious.
Genre Blind: She seems to think of this world as a typical harem manga rather than real life. So when she suggest that Kohinata invite the girls to him on a 3 day 2 night stay on an island resort, most of the girls refuse due to Real Life situations like prior commitments and the fact their parents would not be ok with them going to an island with a boy.
Invisible to Normals: Zepfur (and the game app) can only be seen by Asunaro and the girls; in her words, she can only be seen by the game pieces.
Sleep-Mode Size: Zepfur normally has the form of a little girl in order to save energy. She also takes the form of a stuff doll.
Trash of the Titans: She has absolutely no house cleaning ability, leaving the living room a mess of junk food wrappers in a very short time.

Harem Candidates

In General

The Not-Love Interest: The only reason why they started to hang out with Asunaro at all is because they were forced to by Zeyfur. They do start to appreciate him later on, though.
Power of Trust: In order to save Serika, Suigyoku decided to kidnap everyone to not let anyone kill her. They didn't object at all.

Furuwada Serika

Friendless Background: Before the harem game, she was a loner.
Kuudere: She doesn't interact with the cast that much.
The Smart Girl: She is the one who makes plans on how to not lose this game for the harem team.
Self-Sacrifice Scheme: Decides to be the one who will lose a heart in order to win the third game, making herself an easy target to betray.

Tatewaki Saya

Good Parents: Her dad refused to leave her when he was ostracized for the fact she is not a boy.
Following in Relative's Footsteps: Loves her family and decided to prove that a woman can be a worthy kendo master.
Heir to the Dojo

Yumizuka Liru

Baby Talk: To add to her young childlike look, she also talks like this.
Mangaka: What she is trying to become to earn money for her family.
Older Than They Look: She is the same age as the other girls, but looks and acts like a middle-schooler.
Security Blanket: Often carries a stuffed doll with her.

Heather Shinonome

Dumb Jock: She is on the way to beat her sister's record in running, but when it comes to the game, she has to rely on Serika's instructions.

Suigyoku Ren

Ambiguously Gay: She is very touchy when shes talking with Serika, suggesting she is only after Kohinata due to being forced to.
Bribing Your Way to Victory: She tries to use her vast wealth to get Kohinata's attention.
Early-Bird Cameo: She is briefly shown in a small panel in Chapter 0.
Jerk with a Heart of Gold: Despite being arrogant, she often is the one who makes best decisions for the group.
The Ojou: She is very wealthy and daughter of a powerful businessman.
The Social Darwinist: She uses this as a justification for wanting to win the game rather than work with the others.
Student Council President: She is this for their school.
The Tease: The other girls were able to convince Kohinata that she was this and just manipulating his feelings for her own amusement. This caused her to lose all the hearts she won in the 2nd game.

Konohana Wakako