The rapist is ida, her awakening in bdsm made her unable to contain and gets too excited with her play.
The liar and swindler is the mommy type, forgot her name, she believes her own words too much and lies to herself about being the killer, she tries to kill mc and ml but is stopped.
The killer is the timid one. She feings obedience to a stronger person and manipulates them to kill for her sake. She is the one that convinced the liar to become a killer and attempted to get rid of mc.
The ml isn't rich at all he is a scripted character to gain views, he wants a partner that can stand for herself and loves him truly, his dream is to have a business run by both as husband and wife.
The mc is the winner, her debt is paid by the organizers and the views generated, and still got a 30m yen bonus which is used to start a cafeteria. She does marry ml
Ida starts a business on her own, selling bdsm stuff, with her focus being cheap but safe equipment. She recruits the one who was beaten up as a bodyguard for her and her clients when she shows them their product, she has to step in and stop Ida.
the black haired one is an actress and becomes popular after everything, she is friends with mc
Ida tries to recruit mc (and everyone on the contest) for her company, she declines but says that she aims to become a lawyer, when she gets her degree, she will work with ida.
The killer left and no one knows about her whereabouts, mc gets a letter from her stating that if mc becomes a lawyer and she is caught, she wants mc to represent her, but so far she recons she will never be caught.
The liar was left on a mental institute and stoped from believeing her delutions, she is popular as she is seen as a tragic figure.